Originally Posted by FranktheTank
Well, depends on what you call a power filter. If it's one of those hang on the back filters, I have a hard time completely counting them. Generally speaking, most HOB filters return water along the surface line, which doesn't really move the water deep in the tank. I never count a protein skimmer, because it does what I just said even more. So take those away from your turnover and you might have half the flow. Then add in the fact you have some dead spots and bam... red slime algae.
But there are other causes for red slime besides just flow.
Actually, from watching things that are caught in the return flow from my powerfilter, I know that the current nearly reaches the bottom of the tank. As for the skimmer, I have an AquaC Remora with the prefilter box. Return water from the skimmer exits at the bottom of the prefilter box, which is near the middle layer of the tank, and that current reaches the bottom of the tank. Personally, I don't really think there's a practical way to completely eliminate dead spots, and I just don't really buy the idea that reaching a certain turnover number will magically solve algae problems.