I've had a mesh cover for nine years and never pulled the cover in the spring to find a green pool. Here's my 10-step process for closing the pool: 1) stretch the cover tight in the fall using water bags and 2" spring clamps, 2) blow off the dry leaves weekly using a leaf blower, 3) add a gallon of shock thru the mesh cover in November, 4) slightly loosen the clamps before the first threat of snow so the cover hangs loose over the inflatable tubes/pillows and doesn't tear with heavy snowfall/snowbuild-up, 5) don't touch the pool until April, 6) stretch and retighten the cover tight in late April after the treat of snowfall is gone, 7) dump another gallon of shock thru the mesh cover in mid-April, 8) pull the cover off the pool in late May/early June pool water is clear with just a hint of fine silt on the bottom, 9) SLAM the pool per Pool School instructions, vacuum the fine silt, run the filter for 24hrs then backwash and recharge the filter, 10) enjoy the pool all summer.
As far as maintaining the water level with a mesh cover here's what I do. I drain the pool down to the return outlet. I don't plug the return outlet. Instead I connect a 10' PVC discharge hose to the return outlet so as rainwater and snowmelt pass through the mesh cover, the excess water immediately exits the pool via the discharge hose connected to the return outlet. The water level is always the same all winter long...it stays level with the bottom of the return outlet. Even when the pool freezes, the ice never builds up at or in the return outlet. Never had a single issue with this method and I live in the frigid Northeast.