I can tell you that an opaque pool cover certainly eliminates the breakdown of chlorine from the UV in sunlight. My own pool is a case for that since it has only 30 ppm FC and with around 3 ppm FC average it loses around 0.8 ppm FC per day being open around 1-2 hours each day, though in practice even having the pool closed still has a loss of around 0.7 ppm FC or so per day. My daily loss appears to be mostly regular chlorine oxidation of stuff in the pool (including a slow oxidation of CYA by chlorine).
I don't know how much the "clear blue" solar covers block UV. If they did, but let visible and infrared light through, then that would be ideal as it would heat the pool without a loss of chlorine from sunlight.
Richard
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