Tip of the Week # 9, Display Tank Black-outs

A while back I had started reading about fellow hobbyists completing a 3 day black out on their reef tanks every 3 months as a part of their routine maintenance.  Starting about 6 months ago, I started blacking out my reef tank for 3 days every two months.  There was no harmful effects to my SPS corals or my carpet anemone.

Some of the Identified Benefits Include:

-Slowing down algae growth
-Very effective to help get rid of cyano when used with other traditional control methods
-When done right, it can add a part of a natural cycle as seen in nature as it can simulate a bid storm without some of the negative effects
-In certain set-ups, it will help to slowly reduce the nitrates and phosphates as the inhabitants would experiences a slowed down metabolism allowing the nutrient removal processes in the aquarium to have a greater impact.

Some Tips for Best Results:

-Only turn off the tank lighting.  Allow the ambient room light to hit the tank so you can feed your fish
-Keep all other equipment running on the set-up.
-Feed you fish about ¼ to 1/3 of the normal amount during the black-out period.
-On smaller tanks, carefully watch your pH levels as the level could drop very low in smaller set-up
-The approach works very well on set-up with refugium or algae scrubbers if you leave the lighting schedule the same for the refugium and algae scrubber
-Complete a larger than normal water change after the blackout due to any algae die-off can release extra nutrients into the water.
-Return to your normal lighting level slowly as to not shock any of your corals and/or anemones
-BTAs can start to move during a black-out period
-This will only temporarily solve algae problems.  Without removing the cause(s) of the algae, it will come back in time.

Some other references for routine aquarium maintenance:






One thought on “Tip of the Week # 9, Display Tank Black-outs”

  1. Faith Eileen Bryan

    To be honest, it never occurred to me to black out the tank, but I can see the advantages now. Considering most fish live in darker environments anyway, this has to be beneficial to the fish, as well as to the ecosystem in which they are now living. Interesting concept, thanks for sharing, Cliff!


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