Anyone heard of, or had experience with flow-reversal?

[mas985]

mas985, so, your whole issue on main drains have everything to do with entrapment, and nothing to do with circulating water?

Not quite. I just think there needs to be a clear benefit before making a modification. MDs don't seem to add any circulation benefit (see below) and they will reduce the flow rate to the skimmer (split flow). The entrapment issue just adds to the argument against them. Let me simplify.

PROS - NONE

CONS - Entrapment, leaks PLUS reduced skimmer action (flow rate is split)

If you were to put two identical pools side by side, one with a MD and one without, you would see absolutely no difference in water quality although because of the skimmer issue, the pool without the MD would have a cleaner surface than the pool with a MD. So what is the point? Keep it simple.

Maybe you missed this in the Main Drain article:

Myth
A main drain is essential in a pool to maintain healthy water.
Science does not support this conclusion. In fact, science concludes just the opposite. In a 2006
issue of Fluent News, the leading manufacturer of computational fluid dynamics software, an
article ran that compared pools with and without drains. The conclusion: there were no
significant differences between the circulations of the two pools. In fact, the skimmer-only pool
was slightly better.iv What is even more disturbing is that on page 50 of this same 2006 issue, the
software was used to model a revolutionary new swim skin technology that was sure to dominate
the upcoming 2008 Olympic Games. Pictured in that review: Michael Phelps, Olympic swimming gold medalist. The swim-speed technology was embraced, but the swim-safety
technology was essentially overlooked by the mainstream media