Rt on Caned Heat. Glad u found something that works better for you.
I can't imagine using anything more than the 8 mil b/c the added weight would make it unimaginable to roll up and take out solo. I followed Mark's (mas985) DIY solar cover roller thread to make my rollers and if I had a heavier, thicker cover it would be unwieldy to remove/handle my rollers. I'm on year 2 with my cover and it's showing wear but mostly where it's attached to my rollers (i.e. tearing). Hopefully, it'll make it to the end of the summer (and it should). So even if I just get two seasons out of it, it served its purpose to save me a lot of water. Thus, the thinnest (and blue) one worked fine for me. We have solar and I got my water hovering around 88, which is awesome. I throw on my rollers and I have checked my pool temp in the AM and it looks like right now I'm just losing 2 degrees overnight. With regards to heat loss, it has also served its purpose well.