Water flow per hour.

Hi,I have two tanks,one is tropical about 100 litres. Powerhead and filter set up has 500 litres per hour max flow rate. This has variable flow settings. Fish in tank are,3 platties,10 white cloud minnows,1 molly, 1 rainbow guppy and a spotted catfish.With various fake plants,driftwood,gravel and ornaments. Is it ok to have the flow at full rate all the time? Other tank is coldwater about 20 litres,housing 4 fancy goldfish. Powerhead has 150 litres per hour max flow .Gravel,plants etc. Same question as for tropical set up. Got both powerheads on full flow now. Should I reduce the flow at night when the fish are resting? Is the flow rate really that critical.All replies welcome.

Yes, infact I would recommend it.

I would also recommend keeping them there. The only instance in which I would not recommend keeping a filter/powerhead at full rate is when it is creating a very strong current that fish have to constantly fight against. If this is happening, reduce the flow rate.

No. Chemical and biological activity in the water doesn't stop, so why cease the filtration that helps control these processes?

Matthew Clark

Thanks for the info,will keep both powerheads on full flow. None of my fish are fighting the current.