Fluval C3 Or C4 For 20 Gallon Tank

Paul Ballenger

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Just started
Hello everyone! I have had my 20 gallon tank set up for about 5 months now, and it is fully cycled. I have 6 Danios and 2 Cory cats in the tank right now. The tank came with a TopFin Silent Stream 20 which moves about 100 gph. My tank is not heavily planted, but about medium. I have about 7 plants and some Marimo moss balls in the tank. I have been doing some research, and have decided to get a Fluval C series filter to replace the TopFin. The TopFin just doesn't seem to keep the water very clean. My question is, should I go with the C3 with 153 gph, or the C4 with 264 gph. I do not want to blast my fish with water current, but I definitely want to keep the tank sparkling. Anyone have experience with either of these filters on a 2o gallon?


Valued Member
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3 years
I have been thinking about the C4 for my 40 Gallon tank. It has the crappy Top Fin as well and I don't like it. I would think either one would be fine for you but the C4 is rated for up to 70 gallon so it may be a bit much. I know you can never have too much filtration but it may create more flow than you want.
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