Before the truly silent dc pumps, I liked a slower flow because it usually meant a quieter pump.
This is important information. I have locked horns with many people over the argument of return pump volume to tank size. There are a slew of opinions but here is my .02. Look at the equipment you have in your sump/return manifold: your skimmer, your heaters, maybe you have a reactor and a UV sterilizer. Let's say your skimmer can effectively skim 550gph, your carbon/GFO reactor 250gph, your UV sterilizer 150gph. If your skimmer is your most efficient piece of equipment and it can effectively skim 550gph, if you're circulating 800gph, you just pumped 250gph of unskimmed (dirty) water back into your DT. Think about how much your filtration system can effectively clean, circulate a little less than that and move water around in your DT with power heads. The reason for tank turnover is to get the unwanted stuff out of the water and bring fresh water and nutrients to your inhabitants. Engineer a system that does that, not one that meets some random predetermined number.
I agree with most of what you say, however you are illustration is assuming a skimmer is 100% effecient and they aren’t, some think there as low as 30% and there effectiveness varies during the day, depending on feeding etc. So if we set flow to this level your 550gph would become approx 185 gph would flow then be enough? I don’t know but I would want more flow than that..
You are right on. I've never seen a need for 10x turnover. Smaller tanks I go about 4x to 5x and the bigger the tank the lower the exchange rate I can get away with. Anything bigger than 400g I find 2x per hour sufficient. 1000gal range+ I find 1x per hour plenty. And as your gorgeous reef demonstrates, less than 1x per hour is absolutely sustainable in multi-thousand gal territoryIMO to have 10x or so through the sump is not necessary. And I've tried, many of the tanks at my work is old and not designed for that kind of flow from the sump and back.
This tank for example is about 10000 litres and the return pump is pumping 6000 litres per hour. I don't know if the results would be better with higher turnaround rate, but I think the tank works fine like it is now
Of course it also depends on the bioload in the tank. If it's very high you might want higher flow and larger skimmer etc.
Otherwise I would put my money on buying stream pumps for good internal flow instead of a really large return pump
Edit. I know this post might seems to be to brag. And I know this is a quite large tank. What I wanted to show was that it's possible to do things in different ways. You don't have to follow all the "rules" for a reef tank.
