Honestly, most of this is about actual experience and what you have to deal with. There is a huge push away from main drains, primarily from the safety aspect of it. It is just like people disliking guns. Most say that because they fear it. Main drains are due all the bad press with people getting hurt over the ages, but with dual main drains that concern is all but eliminated in a residential pool.

I understand the science of boundaries, skin effect, wall adhesion, etc, etc... I keep my pool covered at all times with a solar cover when not in use. A skimmer in that aspect doesn't do much and is prone to clogging by the cover and anything else. If anything with the pump on low I notice mostly small stuff accumulating in there. The main drains are cut in full along with the skimmer.

If anyone would care to re-read my first post on this, I gave all the pertinent information as to what I am experiencing and why I am doing it and what the advantages are to me, personally. To argue any of that is just stupid. I never said it only picks up this and if it keeps the floor clean or not. I know it doesn't. It pulls in anything that is suspended in the water it pulls through it. As I stated I can usually cut the main drains in full, stir the water up around them and have them pull in anything small enough to work through the grills. Everything else gets vacuumed (which isn't much once the spring cleanup and fall leaves are done).

In regards to using the main drains as a feed for heated pool water, it also works in reverse, pulling cool water from the bottom center of the pool and allowing circulating warm water form the returns to work towards the center. Simple water flow dynamics dictate that. And with a strong circular current in the pool (using dual returns and pointing them at a 45 degree angle down and to the right creates quite a bit of current in the pool), which is always present since you heat with the pump on high, you have the best case of allowing for the cool water to be sucked in the main drains.

Again, do it or not, that is all personal choice. I understand pool professionals not wanting to put them in. I understand why they tell their clientele they aren't worth it. But for people like myself that operate a pool the way I do, it isn't even a matter of "should I or shouldn't I?", it is a matter of it is the best solution to deal with draining, heating, cleaning and overall circulation and flow. It is just amazing how people try to say it doesn't do anything when it is obviously pulling water from the lowest point in the pool in the center. Plus it is hilarious when most people that argue you shouldn't put one in are the ones that have them in their own pools already. I could care less if you don't find a value or a need and if you have yours cut off all the time, it makes zero difference to the benefits I am personally experiencing in the operation of my own pool.

If anyone cares to have the same advantages, they are welcome to install them as well. To argue the majority of the above posts is beyond futile and ignorant, since none of what was said applies to anything I stated. I appreciate the argument on the academic level, but in an applied sense, in my pool, for my purposes, none of it matters.

Oh, and in fall when the leaves are flying, it makes a huge difference to still be able to filter the water via the mains drains if the skimmer clogs with leaves... I had it happen last fall when the kids were swimming when it was 50 degrees outside... The pump was on high, the pool heater was running heating the pool and the skimmer was totally filled with leaves... If the main drains would not have been able to supply the water properly the heater would have shut off due to either low flow or too high of heater temps and the kids wouldn't have been able to enjoy it as long as they did. Without main drains that situation would have been ruined since the pool would have started to get cold quickly (and a 3-4 degree drop with the kids playing is a big deal to them being able to enjoy themselves).