When is it most beneficial to remove the (green) safety cover and put down the (blue bubble) solar cover to get the maximum benefit of the increasingly warm solar effect from the sun? Average air temps are still in the mid-50's this time of year, but of course there are super nice sunny days that get near 70. I haven't tested my water temp yet, but I will be tracking it. Just wondering if anyone else along this latitude or north of me has experience with this. Thanks!