- This is a pretty common issue for many different people. I know personally I have more than enough flow in my tank from the canister filter. I could go larger but it would also be complete overkill for my tank. My reactor is 3" diameter PVC and approximately 20" tall. I've had the same issue with both a Hydor 350 and an AquaTop FZ9. Here is an older picture, but the basic setup has not changed at all.