hi guys i wanted to know ? i have a 55 gallon tank with two marineland 400 on it how far should i keep my water level from the top when i mean that you know it has that oak boader at the top how far from that should i keep the water.

I usually keep my water level one or two centimeters below the lip of the HOB filter. I like to make sure that the water splashes on the surface and agitates it enough to allow optimal gas exchange.

This usually translates into one centimeter below the top border.

That's what I do too.

Yeah, I keep mine high enough to muffle to sound of falling water comming from my filter but low enough to where the water at the top get agitated.

thank you very much guys i just put mine about 2cm now it was like way up at the toppast the oak line.