being only a 10 gallon tank, i just have a small penguin biowheel hanging on the back, and a small power head hidden to move the water. the caves are all inter connected. my ph
never got above 8 and i just used some ph
balance chemical and have had no problem. the fish that are in there are just a yellow lab and an albino zebra. they were the smallest that were in my 35 gallon hex. i wanted to try this out because i want to try it in a 37 gallon tall for my jack dempsey. i don't have alot of space in the house right now, so i have to go with smaller size tanks, but hopefully i can have a fish room when we move and am looking forward to a 125 fresh and a 125 reef.