Jardin Fish Tank 4 Layer Sponge Biochemical Water Corner Filter

Have had this running for about two months while hooked to a Tetra Whisper pump for 10gals (also from Amazon excellent pump). Originally, had it in my 20 gallon as a supplemental filter and to keep ammonia/nitrite levels stabilized while I was switching between an HOB filter to a canister filter. Although the pump used for it was not rated for a 20gal I'd like to think it did its job. The shape allows me to tuck it in the back corner behind a plant and it is not visible from the front. There was always debris, fish food, and poop attached to it meaning that it was at least sucking up waste.

About two weeks ago I transferred it a poorly maintained and neglected 5 gallon tank with crabs. After changing the tank the water was still cloudy with algae chunks, exoskeletons, and that white film that comes from stagnant water. Well all the debris eventually got stuck on the surface of the sponge and throughout the day you can see the debris get smaller and smaller as it was broken down by the bacteria I guess. By the next day the water and the sponge was clean as a whistle. It is currently still in my 5 gallon with 2 crabs and about a dozen adolescent guppies and all ammonia/nitrite levels are absolutely fine.

In conclusion this is a good filter overall and an excellent filter for small tanks. I will consider buying more of these for any future small tanks. Also in retrospect there is a 6-layer version that is marginally more expensive but would be better suited for larger tanks with more surface area for bacteria to grow on.

So the description is misleading, though technically perhaps correct. When there is no air flowing through the sponge, it does indeed sink, as advertised. However when you are actually using the sponge the air flow and bubbles is enough to make it float. I tried taping the tube to the side wall or something with no luck, it reallllly wants to float, so I ended up putting it under one of my other decorations to keep it down. I'll likely tie it to a rock or something when the snow thaws and I can go outside and find one.

Aside from that it seems quality, though I can't speak to the longevity as I've only had a few days. For me it's not worth the hassle of returning it to get a different one, but when it needs to be replaced I'll likely not buy the same one.

EDIT!!!!!!!!! About a month in, after the bacteria and gunk had time to colonize on it, it weighed down and tank on it's own, so I upgraded the stars to 4.

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