how many times a hour should the water go through the sump?

[MikeInToronto]

Originally Posted by Mr OM

That part of your statement is not true it would work better under lower flow circumstances,
it would be more effective hanging on the back of your tank than being in the sump with a 10x turnover rate.

I was with you up until this post, and that's mostly because I was having trouble understanding both sides until now. However, a tank + sump is a closed system. The amount of water running through the sump should be irrelevant. It would be the same as a HOB skimmer running in a sumpless tank with 100x turnover using just powerheads. In this case, the DT is just like a big sump (since there is no sump).

Water in the sump is the same water as the DT. There is no special separation between the two except the OF, a pump, and some pipe.

The concept that "a sump is not a filter" is a good one. A sump really is nothing except a place to store equipment.

Now if your argument is that a low-flow overflow extracts surfactants better, perhaps you can discuss that more.