Is my filter working?

[JackBinimbul]

Hey, guys. I'm still waiting for my 20g long to cycle. This is my first tank and I'm still very much a newb.

I'm using two sponge filters with a 40g air pump and airline valves. They are both blowing good bubbles and creating surface current, but how do I know if they are filtering?

My dwarf hairgrass isn't moving or otherwise suggesting a bottom current of any sort and I can't see any indication that water or detritus is being drawn into the sponge filters. When I dose with fish food for the ammonia, I see the food being pushed away by the current and eventually settling on the bottom, but I never see it drawn toward the sponges.

Is this normal?

[V227]

A steady current of water and micro nutrients are being pulled into and through the sponges.
This feeds the rapidly growing bed of benificial bacteria. You're really not going to see a sponge filter suck up a lot of excess waste.
Big power filters like AC 110''S or FX 6's generate big currents that will suck up a lot of waste suspended in the water column.
When feeding fish, it's best not to depend on any filter to rid the tank of excess food. Careful feedings coupled with a good cleanup crew of catfish, Loaches and snails is a better solution
Don't forget the weekly big WC..

[JackBinimbul]

Ah, I'm not at all worried about these filters keeping the water "clean". I do weekly changes.

I was just concerned that they weren't working at all. If they aren't filtering, they won't pull enough "food" in for the bacteria to grow. I did test it though by pulling the output tube out of the water and clearly water was being expelled, so it's working. I'm just surprised at how gentle the draw is compared to the output.

I'm also not feeding fish at this point. I'm doing a fishless cycle and only using fish food for the ammonia.

[King Fisher]

Food being sucked in shouldn't be a real concern for cycling. When BB starts growing it will grow on just about everything..... substrate, decor and your sponge filter.

[Fresh2o]

To add to this, the substances consumed by the nitrifying bacteria are dissolved in the water column. So as long as there is flow going through the sponges (and any surface in the tank), the BB will have plenty to feed on.