Today I upgraded, at least I hope to have upgraded, my 20 gallon tank from the TopFin 20 HOB to an Azoo Sponge Filter (#9). I’m using the Whisper 20 gallon air pump to go with it.
First impressions? I think it actually creates more of a current than the HOB did. The debris I kicked up when replanting some stem plants that got loose there were bits and pieces floating around in the water so I got a good view of the current. It doesn’t move as much water, but it looks to be moving water in a larger area than the HOB did. It makes a lot of bubbles too… more than I expected. I plan on replacing the HOB in the 10 gallon also because it is hardly pumping any water anymore (impeller problems) but I misjudged the amount of airline tubing I needed and didn’t get enough. Hopefully with that sponge filter (Azoo #11) on the same airpump will limit the bubbles a little in the 20 gallon.
Sponge Filters are not quiet by any means. The air pumps make a loud hum (in my opinion) and then their is the sound of the bubbles themselves. I’m slightly concerned on the whole CO2 issue, where surface disturbance drives out CO2 which the plants greatly need in a natural tank. But, a HOB isn’t exactly gentle on the surface either. Time will tell!