As stated above its a 20 gallon long. I have a small 4" section using a tank divider which holds chaeto and a Tunze 9002 protein skimmer (just set those up last night). An AquaClear70 for filtration. I previously housed pupfish there but moved them to a brackish set up so the tank has sandbed, live rock and my sun corals. I have a small pipe organ frag given to me by LFS in my 10 gallon tank with 80W PC and it's doing quite well but I want to move it and the new pipe organ that is on hold for me into the 20 gallon tank. But if I have to upgrade lighting (option for that size tank would be 130W PC) then I'll have to rethink corals to add. I wanted to add mushrooms but 130W may be too much for them. I'm trying to see if I can get by without having to buy another light. Health of coral more important so if I have to I will.
