how much flow is too much?

[mr_alberta]

It really depends on what you are keeping? In my old tank I had about 8000gph of flow (2 3600GPH closed loops and 1 800gph return) and the tank was 100G. Mind you I was keeping SPS which like the flow.

[Aquattro]

Agreed. I had about 6000gph in my 75, corals loved it, fish were fine with it.

[kwirky]

really depends on what you're keeping. My 120g had 4800gph of flow (seio powerheads and return pump). My softies were good, my sps wanted even more flow, but my lps hated that much flow. Good example of why it's difficult to keep a large assortment of coral in one tank.

[andresont]

Never enough flow for SPS

[Der_Iron_Chef]

The GPH nomenclature is somewhat misleading, though. 3000GPH of flow is not always 3000GPH of flow. For example, if I put a Vortech on the side of my tank, at 3000GPH, it would create more flow than two 1500GPH powerheads/pumps which were pointed diagonally and deflected off the glass.

I think that random current is more important than actual flow (as it creates movement as well, but just a different type of movement), but I don't think we've mastered how to do this just yet.

Just my $0.02