My feedback on main drains in an above ground pool...

[mas985]

Even with just over 4ft of water I can tell a difference in temp between the upper levels and the bottom without the main drains. With them on it is drastically different.

Within the first few minutes of the pump turning on, I would agree but I think you would have to agree that at some point even without a MD, the water temps would eventually equalize. It is illogical to think that the water temps would remain different at the top and bottom of the pool forever while the pump is running and constantly mixing the water. Even with a single return pointed horizontally, you would see with a dye test, return water mixing with the pool water at all levels of the pool. I really don't think it would take long at all for the temperatures to equalize.


But let me be clear, I am not disputing that MDs help to equalize the temperature difference. What I am saying is that there are other ways to accomplish same thing and they are equally as effective. As I mentioned before, I have one of my returns pointed down to my deep end and the deep end temperature at 9' equalizes very quickly, within minutes. So instead of a MD, you could have added a lower return and had the same results.

I would argue your assumption that since chemicals mix that temperature variances are also nil. That is far from the case.

Why would it not be the case? Both heat and chemicals move along with the water currents as they are both part of the water. Seems logical to me.

you have no point of reference other than flawed studies to fall back upon.

Actually I do, my own measurements and observations as well as a few posts from other POs that have pools without MDs and have no such problem with temperature difference. But why do you think these studies are flawed? They were performed by well respected universities and organizations. If you have any other contradictory scientific evidence then please share it. My point with the studies is that somebody actually went to the trouble of running experiments and simulations and documenting the results. This is what engineers and scientist do to confirm hypotheses.


I understand your reluctance to accept this evidence because you went to the expense and trouble of installing the MD and you really want it to have a benefit that you could not possibly have achieved in any other way but to me, the evidence is indisputable.