I have a 1250 l/hr pro 3 with a diffuser on my 3ft zebra tank and the zebs love the flow. I have a great dead spot close to the intake where are the poop collects so I just siphon that out before I feed each evening. I agree with Mac, it's easy when used as a biological filter, mine has been on the tank now since December and I haven't touched it since it's been on as I have a sponge over the intake so nothing solid gets into it.