This was my eighth opening with a mesh safety cover. It is still in great shape. I usually open to some dirt and leaves in the pool, but generally clear water. However, last season I opened to a swamp - didn't drain the water down so the cover sat in some water - we had a lot of hot days, so I had stringy gren algae . This year, I drained the water down, and opened yesterday to a very green dirty pool. We did have some warm days. Next year I am going to pull the cover back and put in some chlorine, or else open earlier. It is amazing how a swamp can go to a light green in 24 hours with mega doses of bleach I think when I need a new cover I will go with the solid with the drain, unless they come out with something better.