I know what you mean about the crud. We kept dumping it in when the wind blew as we were rolling it up. My skimmers {2} are very well placed for collecting off of the surface water.
The pool itself is 20 x 44 lazy ell with grecian ends. A very clumbsy dimension for the cover.

By the way, Sunday night the air temperature went down to 52 degrees. At 8 AM the pool water was 72 degrees, a 9 degree loss. My theory is that the pool structure below the water acts as a bit of a heat sink. Once the gas heater is turned off, the structure begins to return its heat to the pool water, slowing the heat loss. But it certainly does lose heat faster over time than with a cover. Under the above conditions, we probably will only swim in the pool one more time before we close it.