Winter Swimming Pool Covers
These Offer Benfits as Well as Drawbacks
Winter covers are essentially giant tarps that you use to cover your pool when you close it for the winter.
You can purchase them in the size meant for your pool. Keep in mind that the actual size of the tarp is larger than the size of the pool, so that you have a sufficient amount of cover on the perimeter to hold it down, either with water bags or some other sort of weight. The water bag type of weight can be a bit of a hassle and messy, but on the upside you don't have to worry about what would happen if it fell in the pool. If you were using cinder blocks to hold the cover in place, you're running the risk of destroying a large section of liner if it got dragged into the pool somehow.
Winter covers generally do a better job of keeping the pool water cleaner than do the basic safety cover. However, if you have kids, keep in mind that winter covers are not the least bit safe, and can even potentially cause trouble for even able adults who might accidentally fall on such a cover. Such covers could potentially envelope anyone who fell onto it, and make it far more difficult to get out of the pool than it normally would be. If you want to use one of these covers, be sure you've locked up the pool area securely to minimize the risk of accidents.