Well I had to make a trip to the pool store and the pool guy once again convinced me the most expensive option is the one I should take. He says with a mesh cover I have to keep the pump running 8 to 12 hours a day or algae will stain the pool and ruin the liner etc. Last year I just shut everything down and put on the mesh cover. It was dark geen water when I opened but a few days belach fixed that. He says to run the pump and test PH regularly to make sure it is in balance to keep from ruining the heater and liner. SO did I just get lucky last year when I shut everything down or is the pool guy just trying to make sure I'm using chemicals year round. Also how can I test the water with the loop lock bolted down I don't want to have to get the pry bar out just to get to the water. Also I'm afraid even with a timer on the pump and running 4 hours a day that something will freeze.