QUESTION

[dsuperman]

What would be the optimum volume of air for a sponge filter and by extension ,a box filter filled with polyfil and gravel/ceramic rings? Would it be fast? slow? Faster airflow would mean stronger mechanical filtration but how is biological filtration effected?

[stevem]

There is no easy answer to that; it really has a lot to do with the fish.
Some fish need very slow flow especially when breeding.
But that being said you don't want a lot of flow just blowing through the sponge it would not hold much of the live bacteria.
a nice even flow of bubbles is usually good. A goo air diffuser is also important, and I change them regularly.

Aslo clean out the sponges in water change water, never in tap water. The cloramines will kill off the bacteria.

[dsuperman]

Thanks for the reply,i was wondering if there was an optimum in general. I also think faster flow would hamper biological but can't say for sure. Joe Gargas down in florida states that all filter media can be rinsed under any tap on a regular basis,that there is enough bio in the water and on the glass, even a barebottomed tank to replenish itself quickly. I don't do that, i usually have 2 filters in a tank,only rinsing one at a time.

[stevem]

I do the same, and do not agree with what he says.
I have seen spike when cleaning too much.

[KC2PED]

I am with you guys
I currently have two sponge filters and a canister filter on my 20 gal goldfish tank
I only clean one filter each week and only clean the sponges in tap water about twice a year and neverclean the Matrix from the canister filter in tap water
The sponges in the canister filter are so full of muck that they have to be cleaned in running water
When I do major water changes once a month I only vacuum half of the gravel and don't do a filter cleaning that week

[stevem]

that sounds fine, with 3 filters cleaning one a week it take 3 weeks to complete.
giving time for them to colonize with new bacteria.