Sponge filters!

[convict360]

My rays liked to use it as an elevator to raise them to the surface quickly, then they soar down the glass or suction cup to it. If your still running air I wouldn't be concerned in the slightest, if they are riding the current chances are surface agitation is fine. I keep my sponge filters in my sump without air running to them and I'm curious if they would be effective as an instant start up, I'm not sure that they maintain a similar bacteria colony when unpowered.

This is something I've often wondered too, I'm guessing that if you have an air powered sponge; which you then uncouple and throw say in a sump, I'd imagine it to still have a bacterial colony of some extent, but not as much as it was when powered. Maybe just mostly on the outside, rather than all through it.

But that's just conjecture, not based on any evidence whatsoever

 

[Woefulrelic]

This is something I've often wondered too, I'm guessing that if you have an air powered sponge; which you then uncouple and throw say in a sump, I'd imagine it to still have a bacterial colony of some extent, but not as much as it was when powered. Maybe just mostly on the outside, rather than all through it.

But that's just conjecture, not based on any evidence whatsoever

I would be inclined to agree, which is why I've done it. I suppose I'll get around to powering them in a tank eventually and report back.

 

[Swampgorilla]

I'm in love with sponge filters. There is nothing like breaking out and setting up a hospital tank and throwing a sponge filter and knowing that you immediately have the nitrifying bacteria to keep the tank safe.

You can use them just about anywhere - including the sump. I've even thought of cutting up some of my seeded sponges and throwing in with the bio material in new canister filters to quickly build up nitrifying bacteria in those. I believe it would work.