When you set out to plumb an aquarium set-up with a sump, the more planning / thought you put into the original set-up, the better it will be in the long run. This is not a very hard thing to do at all, if you focus on the basics and understand them. I tend to think of it in flowing different steps: A) Planning of your flow rates, B) planning the material types and sizes, and C) installation / set-up of the plumbing system. All of what you are about to read below is based on my experiences with various data from some North American manufactures of plumbing products (IPEX, Canplas, and Boshart) which is also detailed in the American Society for Testing and Materials (ASTM) standards.
I will explain what I mean by each step then I will show you examples from one of my reef tanks

Note: you have to keep in mind, there may be variation in the plumbing products available to you based on the national building codes of the country that you live in along with local regulations. The below applies to almost all of Canada and the United States. The products available to you may vary.
A) Planning Flow Rates
With every system, you need to know how much flow you will need. Typically this is calculated in gallons per hour (GPH). For example, most people feel a flow through their sumps of 10 times the display tank volume is suitable.  If you have a 120 gallon display tank, then that would mean you will need 1200 gph of flow. But that is only a general guideline.  Your exact flow rate could be higher or lower depending on the equipment in the sump or what you are planning to use the sump for. Once you have determined the flow rate you will need, you will need to apply this target flow rate differently to both your drain line and your return line. The 10X flow rate is typically a good base to start working from and can apply to almost all typical salt water setups.  Some people prefer high flow through their sumps. Fresh water setups typically use a little lower flow rates, around 4 to 6 times the display tank volume is more common.
Drain lines are the lines bring water down from the display tank into the sump. There are many different approaches to achieving this, but mainly fall into one of two categories: Siphon based systems, or a Gravity system (which involves drilling a hole in your tank). With either set-up, one of the bigger factors to consider is the flow rates under extremely little to no pressure. Both types of drains are very similar in GPH (no real significant differences) and these types of drains are discussed in my example here the end of the article. Whatever choice you make, you have to make sure the drain line can also handle the flow you want to put through the sump.
Return lines are the pressurized lines that run from the return pump back into the display tank. There are three factors that are very important to consider here: flow rates, pressure, and the types and numbers of fittings used.
B) Planning Material Types and Sizes
With all aquarium setups (both salt water and fresh water), you have to make sure the pipe and fittings you use to plumb your system are both meant for potable water (can safely handle drinking water) and is resistant to corrosion and scaling. You can ensure those requirements are met by using one of the below material types
ABS (Acrylonitrile Butadiene Styrene). Typically only used for drainage in homes as it cannot withstand much pressure or heat. This is typically black in color. ABS is the cheapest pipe and fittings that can be used. It is only suitable for drain lines and should not be used for pressurized applications.
PVC (Polyvinyl Chloride). Most commonly used as it can handle a range of pressure and some heat. It can be used in residential and commercial drinking water supply (cold water supply only). It usually is the most economical choice for almost all aquarium setups as well as being the most commonly used for pressurized and drain lines.You can get it in both in flexible and rigid pipe (flexible PVC has lower pressure ratings). This is typically white in color.
CPVC (Chlorinated Polyvinyl Chloride). Most commonly used in commercial and/or industrial applications. Can handle both hot and cold drinking water supply. This is typically a shade of grey in color. Although this can be used in an aquarium set-up, it is one of the more expensive options.
PEX (Cross-Linked Polyethylene). Slowly becoming the most used product in the construction of new homes for both the hot and cold drinking water supplies. Is made both in flexible and rigid pipe while maintaining the same pressure rating. PEX is typically a white, almost transparent color. Although this can be used for both pressurized and drain lines, it also is a very expensive option as you need special tools when connecting PEX fittings.
PVC and CPVC are also available in different grades / thicknesses to allow for higher pressure and higher heat limits on both the pipe and fittings. This is done through using the Schedule System. The wall thickness of the pipe and fittings is designated with a “schedule” number. The range from sch (schedule) 40 all the way up to sch 160. Typically you will find sch 40 (regular) and schedule 80 (extra heavy) available in most hardware stores. Schedule 120 and 160 is not commonly used or available in retail stores.

For PVC pipe and fittings, The general rule of thumb is that any pressurized application that would require your set-up to have below 2 inch pipe can / should be completed in schedule 40. Anything higher (ie.. 2 and 2 ½ inch applications) would require schedule 80. That may vary based on exact conditions. You would not have to worry about up-grading to sch 80 pipe unless your system would require around 5,500 gph of flow (or higher flow) through a single plumbing line.
For ease of identification, most manufactures make regular PVC (sch 40) white in color while they make sch 80 in grey. Not all manufactures will do this. It’s always best to read the markings and labeling on the fittings or pipe just to make sure.
The below charts summarized flow rates by: no pressure, average pressure applications, and the maximum pressure that the pipe and fittings can handle in standard PVC (standard = sch 40). Once I start to talk about an example of plumbing a sump, I will be referring back to these charts
(GPH = Gallons Per Hour )

And just to clear up some of the terminology used, ID = Inside Diameter while OD = Outside Diameter.

Loss of flow
Once thing to keep in mind, when planning your plumbing set-up the pump should be the last thing you choose. The reason for this is that you need to know how much loss of flow you will have from your plumbing design. Each time you add a 90 degree elbow, or a swing check valve, you will lose some flow because of these additions to your plumbing line. The below list are more of a rule of thumb with calculating flow loss of your pressurized return line only. They may not be 100% accurate, as many other factors can effect these calculations. They will be close enough for you to get an accurate estimate of the flow reduction. The below factors will become very important when planning your set-up.
• A loss of 75 to 125 GPH for each foot of height (from the pump to the display tank return)
• A loss of 50 to 75 GPH for each 90 degree elbow
• A loss of 30 to 50 GPH for each 45 degree elbow
• A loss of 50 to 75 GPH for each swing check valve
• A loss of 20 to 40 GPH for each ball valve
• A loss of ~ 3 to 5 GPH for each union

I will also be referring back to this information latter when I show how I planned the plumbing layout of my sump.

C) Planning the set-up/Installation.
We have already discussed the typical sizes and material available for your pipe, now it might be best to talk about fittings, other than the more common fittings pictured below. This will help you when it comes time to plan each line in your plumbing.

Below are some of the other fittings that typically use and most likely can be used in your set-up.

PVC Unions

These are very useful fittings to have in your set-up. It can allow you to quickly disconnect a part of the system and then reconnect again without have to worry about gluing or resealing anything. A perfect example of this would be using a union to connect your return pump to the system. This way, you could quickly remove the pump from the plumbing, clean it, then reconnect the pump with a minimal amount of down-time. On more complicated set-ups, it allows for building the plumbing system in different sections before quickly connecting it together. Using unions is also a good idea when working in tight / small paces as you can assemble the lines elsewhere before connecting the system together. They come in standard and sch 80 PVC for both socket weld and screwed / threaded connections

Bulk-head flanges

On a set-up that uses a tank with drilled holes in the glass, the bulk head flange attaches to this hole allowing us to attach plumbing lines to each side of the hole while giving us a water tight seal to the glass that will withstand pressure. They can also come in regular and sch 80 PVC for both socket weld and screwed / threaded connections. The most common bulk head flanges are threaded.

Valves
There are three main types of valves that are the most common in aquarium set-ups, swing check valves, ball check valves, and ball valves. Each has a different use in a plumbing setup.
Swing check valves allow for water movement in only one direction. It has a plate / door inside the valve which will swing open when pressure is apply to only one side of it. It will swing shut when pressure is applied to the other side. Many people install check valves on the return line to their main tank to help prevent water draining back into the sump should the return pump stop working (ie.. if the power goes off). There are a few different types of check valve out there, but the swing check valve is among the most common one used. The better quality swing check valves are design to work without a spring assembly but they will restrict the flow a little. They are available in regular and sch 80 PVC for both socket weld and screwed / threaded connections. The diagram below will show you how the inside of a swing check valve works. Exact designs vary among different manufactures

Ball check valves have the same purpose as compared to a swing check valve. Ball check valve are another type of very simple check valve to only allow water to flow in one direction through the valve.  The valve uses a PVC ball and the force of the water to work.  When water is flowing through the valve in the intended direction of flow, the water will hold the ball up against 4 PVC rails inside the body of the valve.  These rails allow enough spacing around the ball for water to freely move around it.  Only one of the internal rails is shown in the below diagram.

When the direct of the flow changes to the opposite of the intended direction of flow, the ball will be pushed back to rest on a rubber gasket and prevent any flow from getting past it.

The below is a picture of a ball check valve that I used on a larger reef tank.  The picture was taken early on when plumbing it all together.

Please note, a ball check valve works best when installed on a vertical line, not a horizontal line like pictured above.

Ball valves are used to control flow and/or to shut off flow. It is basically a ball with a hole drilled completely through it that is also has the same inside diameter as the pipe it is connected to. When the handle is turned in the same direction of the pipe, the hole lines up with the pipe and the valve is fully open. When the handle is turned in the opposite direction of the pipe, the hole turned the other way and the valve is completely closed. These are also available in regular and sch 80 PVC for both socket weld and screwed connections.

Miscellaneous adapter / fittings
There are a ton of different fittings designed to be used in certain situations that you may come across like: reducing sizes (glued or threaded or both), increasing sizes (glued or threaded or both), going from threaded to glued fittings, or going from glued to threaded fittings. I’ve only mentioned and provided pictures of a few of those types of fittings here to give you an idea of what is available out there.

Drilled or not drilled
One of the last things you will need to decide is if your display tank will be drilled or not. If the tank will be drilled, it would also be recommended that you have a internal or external overflow for the drain line. I always recommend a drilled tank.
Putting it all together
As previously mentioned, there are two traditional ways of connecting your plumbing system together when using PVC and/or ABS materials. One method involves using a combination of threaded fittings and solvent weld (AKA gluing), and a second of using only solvent welded (glued) fittings.
Using Threaded Fittings
This is a fairly easy method to use. There are three things you have to keep in mind:
1) You will need to use thread tape. In pressurized lines, this will fill in the small gaps between the threads and prevent any leaks. It will also help to keep the two fitting tight together. Just make sure you wrap the tape around the threads very tightly and in the opposite direction of the threads so it will not become “un-wound” or bunch up in one spot when you screw the fittings together (see below pic).

2) Do not use / connect threaded fittings made from different materials together. The reason being is that different materials will have different expansion rates when/if they are heated up or get very cold. This will likely cause leaks even when thread tape is applied.

3) Unless you are a skilled pipe fitter by trade, you will need to use adapters to transition from threaded fittings to solvent weld fittings. The reason being is that at some point you are going to need to have a piece of pipe cut to fit a portion of one of your lines. Unless you can have the ends thread to the exact length and depth of the fittings, you going to have to use solvents and adapter to transition between the two connection methods.

Solvent Welding
This is my preferred method. When it is done correctly the bond between the fittings will outlast the pipe and fittings themselves. Solvent Weld is commonly referred to as gluing even though it is not a gluing process at all. The solvent cement actually starts to melt or soften the outer layers of the PVC or ABS when it is applied to the pipe and fitting. When the fitting and pipe are then placed together, the soften materials will now become fused together. It will start to harden in sections, become dry to the touch in about 10 minutes, and will be fully cured and safe to use in 24 hours.

There is a specific type of solvent for each type (and sch) of plastic pipe. It is extremely important to use the correct solvent as it contains an element of the material dissolved in chemical called tetrahydrofuran which allows for the material of both peaces to become fused together. If you use the incorrect solvent, the bond between the two fittings will fail over time assuming one forms at all. When correctly used, the bond between the two fittings will be unbreakable.

With certain types of plastic pipe and fittings, a primer is also suggested for use. This mostly applies to the thicker plastics (like sch 120 or 160), or fittings with finishes that looks like they are highly polished with a mirror-like finish. For PVC and ABS applications, primers would not be required. Additionally, when joining different types of materials (like Regular PVC and sch 80 PVC) you will need both a primer and a solvent meant for using both types of materials or you will not get a bond that will last over time. These are commonly referred to as transition cements / glues.

I would also recommend using a solvent that has low VOC and (in Canada and the USA) meets on of the following ASTM standards: ASTM D2564 ASTM F656, ASTM D2235, ASTM F493, ASTM D3138, and ASTM 2235. Those two statements (Low VOC and one of the previously listed ASTM standards) should appear in the bottle.

Below is how I put together the plumbing set-up for my 120 gallon tank using a 55 gallon tank as the sump. I tried to lay it out in little more detailed steps that I took going from planning the set-up right to installing the plumbing. Please keep in mind, this is just one way to set-up and install plumbing in a sump setup. There are many other way to approach this. I am only speaking to the way that I have done this to hopefully give you ideas on how to approach your set-up.

Now for the first stage – A) Planning the flow rates

Step 1 : How much flow through the display tank
I had decided that I would use the traditional rule of thumb. I set my goal to have 10 times the display tank volume flowing through the sump. That flow rate is very close to the maximum recommended flow for my skimmer and I can add a powerhead to the live rock compartment as that would be the only compartment which requires a higher flow rate. As I have a 120 gallon display tank, that would mean I need 1,200 GPH of flow. But I am willing to settle for anything between 1,000 and 1,400 gph

Step 2: Drilled tank or not (gravity feed or Siphon based drain line) ?

When it comes to gravity based drains, there are two common approaches to control the air/water mixture in order to get a silent drain.  One approach involves using two drain lines , one line containing a valve to restrict the water flow to match the air flow (resulting in a silent drain), and the second is used as a backup drain should the first main drain line become clogged.  This type of approach as a few different common names, like: herbie overflow,  bean animal, ocean to ocean

The second approach involves using a single drain line and controlling / restricting the airflow to create a silent drain. This is commonly referred to as a Duriso Standpipe.  This is my preferred approach as the plumbing is easier to setup and, in my own opinion, less likely to become clogged as you are not restricting the flow of water inside the drain.
As I purchased a new tank, I got one that was already drilled for a return line and a drain line with an internal overflow, I set up a duriso standpipe. Gravity based drains are my preferred method to set up a tank as you can calculate the amount of water that can drain back into the sump should your return pump stop working preventing any water on the floor. Both of my reef tanks have been set-up that way as we get frequent power failures were we live. I chose gravity feed system over a siphon based system for a few different reasons. The least of which is that I feel I can trust gravity feed system not to fail and a gravity based system makes the least amount of noise when assembled correctly.

The pic below shows a Durso stand pipe along with one that I used on my 90 gallon reef tank

Water flows in through the 90 degree elbow at the top and down the pipe through the bulkhead flange and into the plumbing line to the sump. At the very top is a air hole which allows a steady, even flow of water. This will give you a extremely quiet drain line. There is no real set size for the air hole. It can be trial and error. I had made a adjustable air hole by drilling a 5/8 inch hole through the side of the cap and the side of the standpipe. You adjust it by slighting turning the cap to make the hole smaller or bigger which controls the flow of air. Through using an adjustable air hole, you can get the maximum flow and keep the drain extremely quiet (pic below). You can also use a oversized hole (such as ¾ inch) and an air valve as well.
The one disadvantage of a Durso standpipe with a internal overflow is that uneaten food, sludge, etc, can accumulate in the bottom and sides of the overflow over time. This is a minor problem, and really not a big deal. But for this reason I recommend using all slip fittings in the construction of the standpipe, and not gluing the standpipe to the bulkhead. If left unglued, when the interior of the overflow accumulates too much sludge, you can simply scrub around inside the box to loosen things up and pull the standpipe out of the bulkhead. If you choose to drill your own tank, the below link explains the steps of that process.

http://www.aquaticcommunity.com/aquariumforum/showthread.php?t=76407

Just remember you must make the hole ½ to ¾ inches larger than the pipe and fitting size the bulk head flange is rated for. For example, if you want a 1” bulk head flange you will need a 1 ¾ inch hole in your tank.

The Siphon set up is a little more involved. Below is the most common design used.

It is designed to be a non-break siphon. If the power goes out, the tank will only drain down to the point of the intake being out of the water and it is said to start draining again once the return pump comes back on the water line is above the intake. I have never tried one so I do not know how well they actually work. I only wanted to mention them here as an alternative to a stand pipe with a drilled tank. The below link can help you build your own siphon based drain system should you chose that type of drain.

http://www.evillabs.net/wiki/index.php/Super_Sucking_Siphon

There are so alternate products available for a siphon based system using pre-assembled overflow boxes like the one in the below link. These products are typically available in stores that carry products for salt water aquariums. One example is in the link below. Once again, I have never used one of these but it is a possible option to look into should you have a tank that cannot be drilled.

http://www.jlaquatics.com/product/of-cs100/CPR+C-Siphon+Aquarium+Overflow+-+CS100+Deluxe+%28800GPH%29.html

B) Material Types and Sizes
Step 3: Choose the pipe and fittings sizes and material types.
First I determine the size of pipe that I will need for my return line. You can always cheat at this step and just go with the same size of pipe and fittings as the outtake on your return pump. But if I did not know that, I would base my decision on a flow rate of 1200 GPH and the fact that I want to use flexible PVC. This leads me to choose a one-inch line. As flexible PVC has a working pressure of 100 psi and at that pressure a 1 inch line will give me ~2220 gph which is more than enough. For a drain line (including the durso stand pipe) I chose 1 ½ inch line as the will give me about 1400 gph of flow which is a little more than I need just to be safe. Either PVC or ABS will be good for this application. I used PVC as I had some left over from another sump I had set-up.

C) Planning the set-up/Installation.

Step 4: plan the layout.
I drew a simple diagram of how I wanted to put the plumbing together. I kept in mind how much room I had in the stand, the size of the sump, and where I wanted to put all of the equipment in the sump so there would be no plumbing lines in the way. I also did not require a swing check valve on either the return line or drain lines as I made sure the sump has room for all the drain-back into the sump from the main tank should the return pump stop working.

Step 5: Calculate the flow loss on the return line.
Based on: 4 feet of height, three 90 degree elbows, two unions, and one ball valve, there would be a estimated loss of 650 gph. This would mean that I would need a return pump with a flow of 1650 to 2100 gph. As the drain line does not have any significant pressure in it, any flow loss due to only two elbows and a union would not be significant.

Step 6: Chose a return pump
I ended up getting a pump with a 1800 gph flow rate which results in a over flow through the sump of 1,150 gph. This also means I do not have to up-grade the size of my pipe and fittings, or increase the size of the. All of the other factors that go into selecting a return pump is a topic best left for another article.

Step 7: Assemble
After getting everything I needed, along with the proper cements, I got started. I first measured and cut the first few pieces of pipe and put together the plumbing lines as I went. I did not use any glues at this point. Once I had everything built and place just the way I wanted it, I marked each joint with a black marker. That way when I took it apart to apply the cement, I just had to line up the two marks on each connection to make sure it was put it back together just as I had dry fitted it together. This gives me the options to adjust things before gluing as well as gluing some of the plumbing system outside where I don’t have to worry as much about making a big mess

While setting the fittings together I had realized I forgot to add a line to run a media reactor. I added that line to the return line using a “t” fitting. This will not have a significant effect on the overall flow

Step 8: Test.
After letting the newly bonded fittings cure for 24 hours, I filled it up with freshwater and fired up the return pump. I found one small leak which was quickly fixed by tightening the bulk head flange. I let it run for a few days until I had the air intake adjusted so the drain line had the least noise.

And just a few pics of the actual set-up

Please feel free to start a thread in the forum to ask any questions you may have.  If you are not already a member, you will need to sign-up first.

http://www.aquaticcommunity.com/aquariumforum/forumdisplay.php?f=62

Note: you have to keep in mind, there may be variation in the plumbing products available to you based on the national building codes of the country that you live in along with local regulations. The below applies to almost all of Canada and the United States. The products available to you may vary.
A) Planning Flow Rates
With every system, you need to know how much flow you will need. Typically this is calculated in gallons per hour (GPH). For example, most people feel a flow through their sumps of 10 times the display tank volume is suitable.  If you have a 120 gallon display tank, then that would mean you will need 1200 gph of flow. But that is only a general guideline.  Your exact flow rate could be higher or lower depending on the equipment in the sump or what you are planning to use the sump for. Once you have determined the flow rate you will need, you will need to apply this target flow rate differently to both your drain line and your return line. The 10X flow rate is typically a good base to start working from and can apply to almost all typical salt water setups.  Some people prefer high flow through their sumps. Fresh water setups typically use a little lower flow rates, around 4 to 6 times the display tank volume is more common.
Drain lines are the lines bring water down from the display tank into the sump. There are many different approaches to achieving this, but mainly fall into one of two categories: Siphon based systems, or a Gravity system (which involves drilling a hole in your tank). With either set-up, one of the bigger factors to consider is the flow rates under extremely little to no pressure. Both types of drains are very similar in GPH (no real significant differences) and these types of drains are discussed in my example here the end of the article. Whatever choice you make, you have to make sure the drain line can also handle the flow you want to put through the sump.
Return lines are the pressurized lines that run from the return pump back into the display tank. There are three factors that are very important to consider here: flow rates, pressure, and the types and numbers of fittings used.
B) Planning Material Types and Sizes
With all aquarium setups (both salt water and fresh water), you have to make sure the pipe and fittings you use to plumb your system are both meant for potable water (can safely handle drinking water) and is resistant to corrosion and scaling. You can ensure those requirements are met by using one of the below material types
ABS (Acrylonitrile Butadiene Styrene). Typically only used for drainage in homes as it cannot withstand much pressure or heat. This is typically black in color. ABS is the cheapest pipe and fittings that can be used. It is only suitable for drain lines and should not be used for pressurized applications.
PVC (Polyvinyl Chloride). Most commonly used as it can handle a range of pressure and some heat. It can be used in residential and commercial drinking water supply (cold water supply only). It usually is the most economical choice for almost all aquarium setups as well as being the most commonly used for pressurized and drain lines.You can get it in both in flexible and rigid pipe (flexible PVC has lower pressure ratings). This is typically white in color.
CPVC (Chlorinated Polyvinyl Chloride). Most commonly used in commercial and/or industrial applications. Can handle both hot and cold drinking water supply. This is typically a shade of grey in color. Although this can be used in an aquarium set-up, it is one of the more expensive options.
PEX (Cross-Linked Polyethylene). Slowly becoming the most used product in the construction of new homes for both the hot and cold drinking water supplies. Is made both in flexible and rigid pipe while maintaining the same pressure rating. PEX is typically a white, almost transparent color. Although this can be used for both pressurized and drain lines, it also is a very expensive option as you need special tools when connecting PEX fittings.
PVC and CPVC are also available in different grades / thicknesses to allow for higher pressure and higher heat limits on both the pipe and fittings. This is done through using the Schedule System. The wall thickness of the pipe and fittings is designated with a “schedule” number. The range from sch (schedule) 40 all the way up to sch 160. Typically you will find sch 40 (regular) and schedule 80 (extra heavy) available in most hardware stores. Schedule 120 and 160 is not commonly used or available in retail stores.

For PVC pipe and fittings, The general rule of thumb is that any pressurized application that would require your set-up to have below 2 inch pipe can / should be completed in schedule 40. Anything higher (ie.. 2 and 2 ½ inch applications) would require schedule 80. That may vary based on exact conditions. You would not have to worry about up-grading to sch 80 pipe unless your system would require around 5,500 gph of flow (or higher flow) through a single plumbing line.
For ease of identification, most manufactures make regular PVC (sch 40) white in color while they make sch 80 in grey. Not all manufactures will do this. It’s always best to read the markings and labeling on the fittings or pipe just to make sure.
The below charts summarized flow rates by: no pressure, average pressure applications, and the maximum pressure that the pipe and fittings can handle in standard PVC (standard = sch 40). Once I start to talk about an example of plumbing a sump, I will be referring back to these charts
(GPH = Gallons Per Hour )

And just to clear up some of the terminology used, ID = Inside Diameter while OD = Outside Diameter.

Loss of flow
Once thing to keep in mind, when planning your plumbing set-up the pump should be the last thing you choose. The reason for this is that you need to know how much loss of flow you will have from your plumbing design. Each time you add a 90 degree elbow, or a swing check valve, you will lose some flow because of these additions to your plumbing line. The below list are more of a rule of thumb with calculating flow loss of your pressurized return line only. They may not be 100% accurate, as many other factors can effect these calculations. They will be close enough for you to get an accurate estimate of the flow reduction. The below factors will become very important when planning your set-up.
• A loss of 75 to 125 GPH for each foot of height (from the pump to the display tank return)
• A loss of 50 to 75 GPH for each 90 degree elbow
• A loss of 30 to 50 GPH for each 45 degree elbow
• A loss of 50 to 75 GPH for each swing check valve
• A loss of 20 to 40 GPH for each ball valve
• A loss of ~ 3 to 5 GPH for each union

I will also be referring back to this information latter when I show how I planned the plumbing layout of my sump.

C) Planning the set-up/Installation.
We have already discussed the typical sizes and material available for your pipe, now it might be best to talk about fittings, other than the more common fittings pictured below. This will help you when it comes time to plan each line in your plumbing.

Below are some of the other fittings that typically use and most likely can be used in your set-up.

PVC Unions

These are very useful fittings to have in your set-up. It can allow you to quickly disconnect a part of the system and then reconnect again without have to worry about gluing or resealing anything. A perfect example of this would be using a union to connect your return pump to the system. This way, you could quickly remove the pump from the plumbing, clean it, then reconnect the pump with a minimal amount of down-time. On more complicated set-ups, it allows for building the plumbing system in different sections before quickly connecting it together. Using unions is also a good idea when working in tight / small paces as you can assemble the lines elsewhere before connecting the system together. They come in standard and sch 80 PVC for both socket weld and screwed / threaded connections

Bulk-head flanges

On a set-up that uses a tank with drilled holes in the glass, the bulk head flange attaches to this hole allowing us to attach plumbing lines to each side of the hole while giving us a water tight seal to the glass that will withstand pressure. They can also come in regular and sch 80 PVC for both socket weld and screwed / threaded connections. The most common bulk head flanges are threaded.

Valves
There are three main types of valves that are the most common in aquarium set-ups, swing check valves, ball check valves, and ball valves. Each has a different use in a plumbing setup.
Swing check valves allow for water movement in only one direction. It has a plate / door inside the valve which will swing open when pressure is apply to only one side of it. It will swing shut when pressure is applied to the other side. Many people install check valves on the return line to their main tank to help prevent water draining back into the sump should the return pump stop working (ie.. if the power goes off). There are a few different types of check valve out there, but the swing check valve is among the most common one used. The better quality swing check valves are design to work without a spring assembly but they will restrict the flow a little. They are available in regular and sch 80 PVC for both socket weld and screwed / threaded connections. The diagram below will show you how the inside of a swing check valve works. Exact designs vary among different manufactures

Ball check valves have the same purpose as compared to a swing check valve. Ball check valve are another type of very simple check valve to only allow water to flow in one direction through the valve.  The valve uses a PVC ball and the force of the water to work.  When water is flowing through the valve in the intended direction of flow, the water will hold the ball up against 4 PVC rails inside the body of the valve.  These rails allow enough spacing around the ball for water to freely move around it.  Only one of the internal rails is shown in the below diagram.

When the direct of the flow changes to the opposite of the intended direction of flow, the ball will be pushed back to rest on a rubber gasket and prevent any flow from getting past it.

The below is a picture of a ball check valve that I used on a larger reef tank.  The picture was taken early on when plumbing it all together.

Please note, a ball check valve works best when installed on a vertical line, not a horizontal line like pictured above.

Ball valves are used to control flow and/or to shut off flow. It is basically a ball with a hole drilled completely through it that is also has the same inside diameter as the pipe it is connected to. When the handle is turned in the same direction of the pipe, the hole lines up with the pipe and the valve is fully open. When the handle is turned in the opposite direction of the pipe, the hole turned the other way and the valve is completely closed. These are also available in regular and sch 80 PVC for both socket weld and screwed connections.

Miscellaneous adapter / fittings
There are a ton of different fittings designed to be used in certain situations that you may come across like: reducing sizes (glued or threaded or both), increasing sizes (glued or threaded or both), going from threaded to glued fittings, or going from glued to threaded fittings. I’ve only mentioned and provided pictures of a few of those types of fittings here to give you an idea of what is available out there.

Drilled or not drilled
One of the last things you will need to decide is if your display tank will be drilled or not. If the tank will be drilled, it would also be recommended that you have a internal or external overflow for the drain line. I always recommend a drilled tank.
Putting it all together
As previously mentioned, there are two traditional ways of connecting your plumbing system together when using PVC and/or ABS materials. One method involves using a combination of threaded fittings and solvent weld (AKA gluing), and a second of using only solvent welded (glued) fittings.
Using Threaded Fittings
This is a fairly easy method to use. There are three things you have to keep in mind:
1) You will need to use thread tape. In pressurized lines, this will fill in the small gaps between the threads and prevent any leaks. It will also help to keep the two fitting tight together. Just make sure you wrap the tape around the threads very tightly and in the opposite direction of the threads so it will not become “un-wound” or bunch up in one spot when you screw the fittings together (see below pic).

2) Do not use / connect threaded fittings made from different materials together. The reason being is that different materials will have different expansion rates when/if they are heated up or get very cold. This will likely cause leaks even when thread tape is applied.

3) Unless you are a skilled pipe fitter by trade, you will need to use adapters to transition from threaded fittings to solvent weld fittings. The reason being is that at some point you are going to need to have a piece of pipe cut to fit a portion of one of your lines. Unless you can have the ends thread to the exact length and depth of the fittings, you going to have to use solvents and adapter to transition between the two connection methods.

Solvent Welding
This is my preferred method. When it is done correctly the bond between the fittings will outlast the pipe and fittings themselves. Solvent Weld is commonly referred to as gluing even though it is not a gluing process at all. The solvent cement actually starts to melt or soften the outer layers of the PVC or ABS when it is applied to the pipe and fitting. When the fitting and pipe are then placed together, the soften materials will now become fused together. It will start to harden in sections, become dry to the touch in about 10 minutes, and will be fully cured and safe to use in 24 hours.

There is a specific type of solvent for each type (and sch) of plastic pipe. It is extremely important to use the correct solvent as it contains an element of the material dissolved in chemical called tetrahydrofuran which allows for the material of both peaces to become fused together. If you use the incorrect solvent, the bond between the two fittings will fail over time assuming one forms at all. When correctly used, the bond between the two fittings will be unbreakable.

With certain types of plastic pipe and fittings, a primer is also suggested for use. This mostly applies to the thicker plastics (like sch 120 or 160), or fittings with finishes that looks like they are highly polished with a mirror-like finish. For PVC and ABS applications, primers would not be required. Additionally, when joining different types of materials (like Regular PVC and sch 80 PVC) you will need both a primer and a solvent meant for using both types of materials or you will not get a bond that will last over time. These are commonly referred to as transition cements / glues.

I would also recommend using a solvent that has low VOC and (in Canada and the USA) meets on of the following ASTM standards: ASTM D2564 ASTM F656, ASTM D2235, ASTM F493, ASTM D3138, and ASTM 2235. Those two statements (Low VOC and one of the previously listed ASTM standards) should appear in the bottle.

Below is how I put together the plumbing set-up for my 120 gallon tank using a 55 gallon tank as the sump. I tried to lay it out in little more detailed steps that I took going from planning the set-up right to installing the plumbing. Please keep in mind, this is just one way to set-up and install plumbing in a sump setup. There are many other way to approach this. I am only speaking to the way that I have done this to hopefully give you ideas on how to approach your set-up.

Now for the first stage – A) Planning the flow rates

Step 1 : How much flow through the display tank
I had decided that I would use the traditional rule of thumb. I set my goal to have 10 times the display tank volume flowing through the sump. That flow rate is very close to the maximum recommended flow for my skimmer and I can add a powerhead to the live rock compartment as that would be the only compartment which requires a higher flow rate. As I have a 120 gallon display tank, that would mean I need 1,200 GPH of flow. But I am willing to settle for anything between 1,000 and 1,400 gph

Step 2: Drilled tank or not (gravity feed or Siphon based drain line) ?

When it comes to gravity based drains, there are two common approaches to control the air/water mixture in order to get a silent drain.  One approach involves using two drain lines , one line containing a valve to restrict the water flow to match the air flow (resulting in a silent drain), and the second is used as a backup drain should the first main drain line become clogged.  This type of approach as a few different common names, like: herbie overflow,  bean animal, ocean to ocean

The second approach involves using a single drain line and controlling / restricting the airflow to create a silent drain. This is commonly referred to as a Duriso Standpipe.  This is my preferred approach as the plumbing is easier to setup and, in my own opinion, less likely to become clogged as you are not restricting the flow of water inside the drain.
As I purchased a new tank, I got one that was already drilled for a return line and a drain line with an internal overflow, I set up a duriso standpipe. Gravity based drains are my preferred method to set up a tank as you can calculate the amount of water that can drain back into the sump should your return pump stop working preventing any water on the floor. Both of my reef tanks have been set-up that way as we get frequent power failures were we live. I chose gravity feed system over a siphon based system for a few different reasons. The least of which is that I feel I can trust gravity feed system not to fail and a gravity based system makes the least amount of noise when assembled correctly.

The pic below shows a Durso stand pipe along with one that I used on my 90 gallon reef tank

Water flows in through the 90 degree elbow at the top and down the pipe through the bulkhead flange and into the plumbing line to the sump. At the very top is a air hole which allows a steady, even flow of water. This will give you a extremely quiet drain line. There is no real set size for the air hole. It can be trial and error. I had made a adjustable air hole by drilling a 5/8 inch hole through the side of the cap and the side of the standpipe. You adjust it by slighting turning the cap to make the hole smaller or bigger which controls the flow of air. Through using an adjustable air hole, you can get the maximum flow and keep the drain extremely quiet (pic below). You can also use a oversized hole (such as ¾ inch) and an air valve as well.
The one disadvantage of a Durso standpipe with a internal overflow is that uneaten food, sludge, etc, can accumulate in the bottom and sides of the overflow over time. This is a minor problem, and really not a big deal. But for this reason I recommend using all slip fittings in the construction of the standpipe, and not gluing the standpipe to the bulkhead. If left unglued, when the interior of the overflow accumulates too much sludge, you can simply scrub around inside the box to loosen things up and pull the standpipe out of the bulkhead. If you choose to drill your own tank, the below link explains the steps of that process.

http://www.aquaticcommunity.com/aquariumforum/showthread.php?t=76407

Just remember you must make the hole ½ to ¾ inches larger than the pipe and fitting size the bulk head flange is rated for. For example, if you want a 1” bulk head flange you will need a 1 ¾ inch hole in your tank.

The Siphon set up is a little more involved. Below is the most common design used.

It is designed to be a non-break siphon. If the power goes out, the tank will only drain down to the point of the intake being out of the water and it is said to start draining again once the return pump comes back on the water line is above the intake. I have never tried one so I do not know how well they actually work. I only wanted to mention them here as an alternative to a stand pipe with a drilled tank. The below link can help you build your own siphon based drain system should you chose that type of drain.

http://www.evillabs.net/wiki/index.php/Super_Sucking_Siphon

There are so alternate products available for a siphon based system using pre-assembled overflow boxes like the one in the below link. These products are typically available in stores that carry products for salt water aquariums. One example is in the link below. Once again, I have never used one of these but it is a possible option to look into should you have a tank that cannot be drilled.

http://www.jlaquatics.com/product/of-cs100/CPR+C-Siphon+Aquarium+Overflow+-+CS100+Deluxe+%28800GPH%29.html

B) Material Types and Sizes
Step 3: Choose the pipe and fittings sizes and material types.
First I determine the size of pipe that I will need for my return line. You can always cheat at this step and just go with the same size of pipe and fittings as the outtake on your return pump. But if I did not know that, I would base my decision on a flow rate of 1200 GPH and the fact that I want to use flexible PVC. This leads me to choose a one-inch line. As flexible PVC has a working pressure of 100 psi and at that pressure a 1 inch line will give me ~2220 gph which is more than enough. For a drain line (including the durso stand pipe) I chose 1 ½ inch line as the will give me about 1400 gph of flow which is a little more than I need just to be safe. Either PVC or ABS will be good for this application. I used PVC as I had some left over from another sump I had set-up.

C) Planning the set-up/Installation.

Step 4: plan the layout.
I drew a simple diagram of how I wanted to put the plumbing together. I kept in mind how much room I had in the stand, the size of the sump, and where I wanted to put all of the equipment in the sump so there would be no plumbing lines in the way. I also did not require a swing check valve on either the return line or drain lines as I made sure the sump has room for all the drain-back into the sump from the main tank should the return pump stop working.

Step 5: Calculate the flow loss on the return line.
Based on: 4 feet of height, three 90 degree elbows, two unions, and one ball valve, there would be a estimated loss of 650 gph. This would mean that I would need a return pump with a flow of 1650 to 2100 gph. As the drain line does not have any significant pressure in it, any flow loss due to only two elbows and a union would not be significant.

Step 6: Chose a return pump
I ended up getting a pump with a 1800 gph flow rate which results in a over flow through the sump of 1,150 gph. This also means I do not have to up-grade the size of my pipe and fittings, or increase the size of the. All of the other factors that go into selecting a return pump is a topic best left for another article.

Step 7: Assemble
After getting everything I needed, along with the proper cements, I got started. I first measured and cut the first few pieces of pipe and put together the plumbing lines as I went. I did not use any glues at this point. Once I had everything built and place just the way I wanted it, I marked each joint with a black marker. That way when I took it apart to apply the cement, I just had to line up the two marks on each connection to make sure it was put it back together just as I had dry fitted it together. This gives me the options to adjust things before gluing as well as gluing some of the plumbing system outside where I don’t have to worry as much about making a big mess

While setting the fittings together I had realized I forgot to add a line to run a media reactor. I added that line to the return line using a “t” fitting. This will not have a significant effect on the overall flow

Step 8: Test.
After letting the newly bonded fittings cure for 24 hours, I filled it up with freshwater and fired up the return pump. I found one small leak which was quickly fixed by tightening the bulk head flange. I let it run for a few days until I had the air intake adjusted so the drain line had the least noise.

And just a few pics of the actual set-up

Please feel free to start a thread in the forum to ask any questions you may have.  If you are not already a member, you will need to sign-up first.

http://www.aquaticcommunity.com/aquariumforum/forumdisplay.php?f=62