This is a low tech tank, no CO2 system, low light and slow growing plants, with maybe 25 inches of fish flesh in it. The tank is very stable and the plants are lush using only half the recommended dose & frequency of excell flourish (liquid CO2 substitute). Those stories about oxygen being problematic in these tall hex tanks isn't true. I have a spray bar on top and a small airstone making turbulance at the top and have no problem with adequate gas exchange. A Fluval 305 and some dedictaed ottos keep it clean.