a hard to answer question… just how much air is right for maximum filtration on a typical sponge filter???

[Magnum Man40 155]

I know I have typical sponge filters rated from 10 gallons to 70 gallons , the lift tubes are different lengths, and different diameters… my air pump is big enough to blow all the water completely out of the lift tube ( too much ) and with valves, can be cut back to one bubble in the lift tube at a time… I suspect optimum water flow is somewhere in between… I could suspect, that as low as 1 bubble in the lift tube makes the water flow, as the bubble rises, and possibly too many bubbles reduces the amount of water the lift tube can hold???

maximum flow or not, I like a good rolling of the water, above the filter, for surface aeration of the water, but not so much that it spits water out of the tank…

thoughts???

 

[gwand39 156]

Each of my tanks has a small pump connected to a sponge filter and/or air stone. I run the pumps full blast for maximum bubbles. The pumps are not powerful enough to spit water out of the tank.

 

[Magnum Man40 155]

my pump runs 3/8 inch lines to the manifold of valves, that step it down to normal air line diameter

 

[Tomsfish18]

Along with how much air you install the length and width of lift tubes effect how much water is drawn through the sponge.
I liked flow as you described. Enough to keep the surface agitated but not spit large amounts of water beyond the tank.
Hard to know how well things are going till you squeeze out your sponges.
One of my pet peeves is seeing keepers using sponge filters without the lift tube at all. That seriously reduces the draw through the sponge.
I know from experience and watching many other breeders that the sponge filter still works without the lift tube but it is not running properly.
Breeders do this a lot since some fish will lay their eggs on any vertical item like a heater or filter tube.
Using an air stone also increases the flow as many smaller bubbles lift more water.
Some sponge filters have an air stone type device installed on them from the get-go.

I used sponge filters small enough to fit in a dip and pour up to almost 6-inch diameter.
Always had at least 2 sponges in every tank except the smaller breeding and fry tanks.
Even with a 2–3-gallon betta tank I used for fry I would install 2 of my smallest sponge filters.

 

[Back in the fold]

When I was a kid I ran my box filters and UGF’s full blast figuring that if a little air was good then a whole lot must be better . A learned man in the aquarium club explained to me that the water was being pushed through between the bubbles and that I should back off a bit to where I could see space between the bubbles . I’ve followed that advice ever since .