20g long sponge filter question....

[lilmissj01]

How big of a sponge should I use in a 20g long? Or, do I go with multiple?...and if so, how many?

[OSagent23]

Sponge filters are rated per gallon. You can get 2 ten gallon sponge filters or 1 twenty gallon sponge filter. Just make sure you have an air pump rated for 20 gallons to run the filter.
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[Hallyx]

Two of these (or similar) running off a Tetra Whisper 20g airpump would handle your biofilter needs.

[ame]http://www.amazon.com/Hydro-Sponge-Filter-I-HS910-Aquarium-Technology/dp/B0002602S2/ref=pd_sim_petsupplies_4[/ame]


One sponge filter and a small HOB would probably work better. And one would back-up the other.