Simply worded, a sump is just a secondary tank that is set-up and linked into a main / display tank as an option for placing equipment as well as providing filtration for the main tank.
If I have learned anything in this hobby it is that there are many many different ways to achieve a healthy and thriving tank. This could not be any truer with how you choose to set up a sump. Likely the best way to approach this topic is to describe the factors that I learned which go into designing your sump and then show you how I set up my sump just as one example. I hope you will find these sump basics helpful.
Why do some hobbyist use sumps ?
Some people would not have a marine tank without a sump while others fell they are not required. Although it can be debated whether or not a sump is required, there are some benefits to having a sump such as:
Are there any drawbacks ?
In short, there can be. Most of the potential drawbacks can be avoided if you understand them and plan your sump to avoid them. These potential drawbacks can be:
If you have decided you want a sump after carefully considering the pros and cons, you are going to want to plan the sump as best you can.
Step 1: The first thing you want to do is decide what you want to use your sump for ?
You can keep almost any type of equipment you want use on you set-up in the sump. Possible equipment to keep there could be: skimmer, heater, media reactors, or calcium reactors just to mention a few possible options.
This could include different types of biological filtration such as: bio-balls, ceramic rings (bio-max), or live rock. Each of these options have many different pros and cons so you should really do your homework first on choosing what type of biological filtration you will use (if any) in your sump.
Once again, many options to consider such as: filter socks, filter floss, or sponges. Each option requires a few little modifications to your design to allow for mechanical filtration if you choose to use this option in your sump
You can consider using: carbon, phosphate removers, or nitrate removers, in your sump just to name a few. You can use this passively (just placing it in there and allowing water to flow over it) or actively in a media reactor.
When it comes to a refugium, they can have many different purposes, but they will all have one thing in common. As an over simplified definition of what a refugium is, it is a refuge from predators. You can grow pods, macro algae, or keep fish in a refugium keeping them safe from threads of other fish or inverts. As mentioned before, you can place the refugium lighting on a reverse cycle to your tank light to help stabilize your PH. Refugiums are a topic best left to discuss on their own.
Most people make their choices of the above based on many different factors. Most of these choices are based on the type of set-up they want to have.
There are many other articles here that cover more details about filtration and equipment options
Step Two: plan your layout
Just a few rules of thumb that I have found to be helpful:
The below picture outlines the three more common approaches planning the layout of your sump. You can choose almost any layout depending on where you want you drain and return lines in you main tank.
Step Three: plan your flow rates
This one likely one of the more debated aspects when it comes to setting up your sump. However, I would say the flow rates of your sump should be based on a few factors.
Refugium –if you have a refugium, you will most likely want a lower flow rate to allow for: natural nitrate removal, accommodate some marine life, or a combination of both. This is the main reason for the layout in the top pic of the above. This way, you can have two different flow rates in the sump, one for the refugium and a second for the equipment and return pump compartment.
Skimmer – most people also match the flow rates of the sump to match the flow rate of their in sump skimmer. This allows for the best performance from your skimmer.
Rule of thumb – some people just go with a 10X main tank volume as there flow rate and then adjust from there.
Step Four: Planning the compartments
Before talking about the compartments, it first might be a good idea to talk about the baffles and bubble traps.
Think of baffles as walls or dividers in your sump that will both separate your compartments, and be used to set the water levels in each compartment. Two baffles used together can also help to direct the flow in your sump compartment moving from top to bottom (or bottom to top) to help circulate the water through more of the compartment. A bubble trap is just three baffles used one after the other to change the direction of the flow three times to help eliminate micro bubbles in the sump’s water. You would typical want to use a bubble trap to eliminate micro bubbles from getting into compartments were they would have a negative effect on any equipment in that compartment. Skimmers and return pumps typically do not perform well with micro bubbles in the water. As a rule of thumb, baffles need to be spaced one inch apart and one inch from the bottom to allow for strong flow rates as well as maintaining a relatively small spacing to help eliminate micro bubbles.
The first step is to determine were you will place your sump after it is set-up so you will have an idea of any potential size limitations. If the sump will be placed in a tank stand, you will have to double check for any height limitations as well. Next I would suggest that after you have planned what the purpose of your sump and the equipment you want, you should actually purchase all of the equipment before completing the sump. Once you have all of your equipment and you can assemble the equipment to confirm how much space will be required for your compartments.
You can now decide if you want to purchase a preassembled sump or purchase a standard sized aquarium that you can make into your sump.
Step Five: Build the Sump and plumb it to the tank
If you have purchased a pre-assembled sump, then you likely will not need to assemble / install any baffles or bubble traps. If you are using a standard sized aquarium, then you will have to install baffles. I would suggest that you first place all of your equipment inside the sump and space it out to where you want it. Now you can use a non permanent marker to mark were your baffles should go. You can also now plan how tall the baffles should be based on the requirements of your equipment (mainly your skimmer) which require a certain depth of water to work in. You will also want to base the height of your baffles to leave enough space in your tank to accept any potential drain back from your main tank in the event of a power failure (this is explained in more detail in my example at the end of this article)
Remove the equipment and carefully measure and mark were your panels will go. You can now purchase glass cut to the size you need and silicone the baffles in place. You will also want to Make sure you space the baffles at least one inch apart.
As for plumbing the sump to your tank, the below article here contains a lot of helpful information on how to plumb a sump and tank together.
Step 6: test
Put it all together and then run the set-up for a while to make sure everything works they way you planned it. The following is an example of how I did the sump in my last reef tank set-up. This is my preferred way to set-up a sump. Hopefully it will give you some ideas on how to set-up yours
My example of how I applied these sump basics in one of my aquariums with a sump
Step – 1
I first decided how big my sump would be. I wanted the biggest one that I could fit in a stand under my display tank. As my display tank is 4’ X 2’ X 2’, I determined the biggest sump I could fit inside the stand would be a standard 55 gallon tank.
I next decided what I wanted to use the sump for. I know I wanted a live rock compartment as large as I could make it. I also wanted to have a skimmer in the sump, two heaters, and still leave room for at least one reactor. I also left it would be important to have a little extra room should I want a second reactor or other equipment latter on. As I wanted as large of a compartment for live rock as I could make, I decided I would set the drain line to flow into that compartment and use a filter sock to catch all the crud along with getting rid of any micro bubbles that would be created by the drain line.
Next I determined how much drain back I would get from the display tank, should the power go out. The display tank is drilled with an internal overflow for the drain. I prefer to use a durso stand pipe in a internal overflow as a drain into the sump as this is the easiest way (IMO) to set-up a drain which can not cause any potential problems should the return pump stop working (like during a power failure). The return line is drilled on the back glass 3 inches from the top of the tank.
To calculate the drain back from the display tank, I took the lowest point of the tank between the top of the internal overflow and the hole drilled for the return line in the back of the tank. The lower of the two was the return line which was 3” from the top of the tank. Using that lower measurement, I was able validate I would get 15 gallons of drain back using the below website:
As an alternative to the above thread, you can also calculate the volume by using the below formula. Keep in mind; it will be about 95 to 98% accurate (IMO). You input the tank (or tank space) dimension using inches and the calculated outcome is in US gallons.
(Length X Width X Height) / 231 = tank volume in gallons
(48 X 24 X 3) / 231 = 14.96 gallons
So now I know I have to leave enough space in the sump of 15 gallons of water
Step – 4
I next planned my flow rates. I set my goal of as close to 10X the display tank volume as I could get. I chose that flow rate based on a few different factors. I knew what skimmer I would be purchasing for the sump so I knew it had a flow rate of 800 to 1000 GPH (gallons per hour) so I wanted the flow to be at least within that range but a little higher would still be OK as well (IMO). I also wanted to have the return pump move as much water in the tank as practical and that nothing that I was planning to use my sump for would need a specific or lower flow rate. I chose the goal of between 1000 and 1200 GPH. That worked out to approx 10 X flow.
The only compartment that I wanted a different flow rate in was the live rock compartment as I wanted an even higher flow rate in there to maximize the biological filtration from the live rock. It was easier for me to add a power head to that compartment to increase the flow without impacting the rest of the sump set-up while still keep my design as simple as possible.
Once I knew the flow I wanted, I planned my plumbing set-up to ensure the plumbing will allow for this flow rate and to determine the correct sized return pump to get that flow through the sump. I used the information in the below article to do that:
Step – 5
The next step for me was to purchase the equipment I was planning to put in my sump. Once I had all of the equipment purchased, I placed them in the sump so I could plan out the size of the compartments and marked were the baffles should be. I also wanted a bubble trap just before the skimmer to get rid of any micro bubbles which the drain line might produce. By doing this I was able to determine the length of each compartment. Next step was to determine the height of the compartments. Using the same formula as listed before, I sized each compartment so the total volume of water in the tank would be no more than 40 gallons to allow the drain back from the tank should the return pump stop working.
Note: The above diagram is not to scale
I could also build my tank stand now as I had the details of the sump so I could make sure everything will fit in the stand and still leave me some room to get at all the equipment without running into any difficulties.
Step – 6
Now that I know how large and tall I wanted each compartment to be, I ordered some pcs of glass to make the baffles and siliconed them in the sump. I spaced the baffles 1 inch apart and made sure the baffles used to direct the water flow down were no less than 1 inch from the bottom of the tanks (closer to 2 inches actually).
Once the silicone had at least 24 hours to cure, I placed the sump in the stand. I hooked up the plumbing and return pump, and tested the set-up with fresh water. When testing everything, I first checked for any leaks. I found and fixed one small leak as I did not tighten one bulk-head flange enough. The most important test was cutting the power to the return pump to make sure the sump would hold all the water that drained back, and that the system would return back to normal once the power failed. Every worked as planned.
Now that I had everything working as I had planned it, I drained the fresh water out of the tank, filled it with mixed salt water, and cycled/stocked that tank from there.
Here are some more pictures of the complete set-up
The Durso Stand Pipe and corner internal overflow
The drain line from the bulk head flange in the internal overflow to the first compartment of the sump. This is the live rock compartment.
The last two compartments of the sump and the plumbing return lines. The middle compartment is for the skimmer and heaters, and the last is for the return pump. I have one ball valve for the return pump, one for a media reactor, and a extra one should I choose to add something else in the future
And the final two pics of the return line coming out of the sump, unto the bulk-head flange at the back of the tank and the return nozzles in the tank.
It’s hard to see, but I did drill a small hole on the top of the last fitting just before the return line splits into two inside the tank. This way, if the return pump quits working the water will not drain below that fitting as the hole will prevent a siphon from being created.
And one full sump picture. I added 45 lbs of live rock and a filter sock to the live rock compartment, and a 1100 GPH power head for extra flow. I did end up moving the heaters in the live rock compartment just for ease of skimmer maintenance. You can see a part of my media reactor which just behind the center support for the stand. Keep in mind, all equipment power cords used on this set-up are plugged into a Ground Fault Interrupter (GFI) electrical outlet to help ensure electrical safety.
Missing fish ?
I almost lost a clown fish to my sump. The reason being is that I only had used egg crate as a guard to prevent fish from getting into the overflow box. Based on what I have read, many people in the hobby have experienced this. As the clown fish was about as wide as the opening in the egg crate, it was only a matter of time before he found his way into the overflow box and got sucked into the drain. I found the poor little guy in the skimmer compartment of the sump. That could have resulted in him getting hurt very bad or much worse. Every sense then I have nick-named him “Lucky”.
To prevent this from happening again, I placed a plastic mesh material over the egg crate.
And just a few examples of my 90 gallon as well. The biggest difference between the two is that I had made a small compartment for the intake to flow into to allow for a bubble trap to eliminate the micro bubbles before reaching the sump without using a filter sock.
The duriso stand pipe
The sump plan
The sump build
Note: the bulkhead flange with a fitting a valve that you see one the sump in the below pic was put there by the past owner of the tank. I did not use it for anything in the sump.
Sump pic 16
As you can see in the above and below pictures, there is a ball valve not currently being used (the one pointing down and attached to the return pump on the right). I placed this valve to help control the flow. I was concerned the return pump I used might have too much flow through the tank. If I ever want to reduce the flow into the tank created by the return pump, I just have to open that bottom valve and redirect some of the flow back into the sump. I prefer this approach instead of using a ball valve on the return line to control the flow through restricting the size of the line. I only use the ball value on the return line to prevent drain back when I remove the pump for routine maintenance.
And the completed sump in use
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Some other good reading: