Solar cover Mil thickness for reel operation

Jun 2, 2009
I have to buy a new cover this year. I purchased a reel last year for our 27' round above ground pool. The cover that came with the pool seemed a bit heavy when it was rolled up on the reel. I was wondering what Mil thickness is optimum for a reel? My reel is located on the end of the pool if that makes a difference. I think a 8 mil cover would be the lightest but probably not the best for keeping it warm and such. So I am leaning towards a 12mil diamond shape one. What do you guys think?



LifeTime Supporter
May 21, 2010
East Hartford, Connecticut
We had a 16 ml clear cover on our 24' above ground - it was heavy when rolled up and pivoting away but super durable and stiff. It was kept out of the sun when rolled up which was huge in maintaining it's life.

We were using a 15 ml clear cover with round bubbles on our 19 x 36 IG pool last year and it really stressed the reel - my DH had to make reinforcements to it to try to eliminate the big sag in the middle. I have heard in several sources that diamond bubbles catch more water in them as the cover is rolled up, so of course that will add to the weight. I have also heard that preventing evaporation is the reason why these covers retain the heat, so thickness wouldn't be a bearing on that; just on longevity.

I've seen online stores selling 5 ml covers even . . I always thought that 8 ml was the thinnest.

I am waiting for shipment of my new 12 ml cover and will be interested in seeing how it compares to the 15 ml. weight-wise.



LifeTime Supporter
TFP Guide
Jun 12, 2011
Do not use a diamond shaped bubble cover with a reel. The diamond shape traps water when rolled up making it very heavy. In fact most places say that use on a reel voids the warranty on both the reel and the cover. There is little difference in the performance of covers. They all prevent evaporative cooling and provide very minimal solar heat gain. The primary difference seems to be in how long they last. I would buy a cheap one and replace it when it's shot.


LifeTime Supporter
Jul 3, 2009
Olney, MD
I have never had one last more than three years (regardless of thickness/weight/storage methods). So I only buy the thinner cheaper ones. The warranties are pretty much a scam because they just prorate and are really only there to make sure you buy your next one from the same company.