Leave sponge in HOB filter?

[supercoupe91]

I have been reading this board off and on for the last year or so when I first started a 20 gallon tank. My tank is fully established and I use an Aqua Clear for water flow only.

I threw out the poly bag and carbon bag...the filter is "rated" for a much larger tank.

I left the sponge in it. Good idea or bad?

[cutietwo]

I leave the black square sponge in my HOB and it works great for me. I think it lessons the microbubbles a little., but i'm not sure by too much.

[jenglish]

If you have live rock I might be more inclined to remove the sponge and add more carbon.

[Loverotties]

+1 What type of tank?

[supercoupe91]

its a standard 20 gallon, power compact light, 7 or 8 lbs of live rock and 1-2 inches of live sand.
nothing but a clean up crew in it, plus a strange rock boring urchin and a brittle star that both came inside a piece of rock i bought.

[jenglish]

Leaving the sponge in can help nitrification (ammonia to nitrate) but not denitrification (nitrate to nitrogen gas that can leave the tank). A sponge is great for a fish only tank but can be a problem for reeftanks that have critters that do not tolerate nitrates well.