Filter rec for 3 gallon hex
Can you recommend a specific filter for a tall 3 gallon hex I am planning at work? I'm trying to keep this as cheap as possible.
I was hoping/assuming I could find a very small internal unit - maybe a sponge - or a canister to keep the mechanicals outside the tank. I was planning on heeping the tank covered to reduce evaporation. But I haven't been able to find anything small or cheap enough.
I could try to rig something up with a powerhead, but most of those options seem either cumbersome, pricey, or both.
So far the best options seem to be a HOB - either the Red Sea nano ot Tetra Whisper 10. I can get either for around $10.
As an initial matter, shouldn't I try to avoid a HOB unit to conserve CO2? I'll probably use Excel for CO2.
I'm not sure if either the Red Sea or Tetra units will fit into the limited space I will have at the top of the tank. Each side of the hex is only 3 1/4" wide, and there is 1 5/8" between back edge of the tank and the back of the light fixture. Any thoughts as to which - if either - will fit?
Or any other thoughts as to filters out there?