I scored a second nature whisper power filter model 2b today at a garage sale for $2. It's an older filter and I googled the heck out of it and can't find anything about gph or anything. The best I could find was an eBay listing with one hanging on the back of a 55 gl. I'm thinking it could do a 20 gl. for sure but if anyone has had any experience I'd love to know. Thanks. It may be for my first A.Ciclid tank 
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