Cover on or off - daytime ?

I don't know what thickness this solar cover is, but it's sky-blue coloured & Not see-through.
For maximum heating: Do I leave the cover on, on sunny days, or take it off?

The pool has a twelve foot deep end & the liner is a much darker colour than the solar cover.
I see on-line that some covers work really well as a green house effect, but I'm not sure if mine is one of them.
( perhaps those covers meant to be left on during sunny days are the ones with the silver-coloured layer...?)

Thanks for your help :)

Heat loss is mainly through evaporation, so IMHO, keeping the cover on or off in the day depends a lot on the weather. If it's a really warm day without much wind, I don't worry about the cover off. If there is a decent wind, or the air temperature is a good amount lower than the water, I leave the cover on.

If it's a day where the pool will be used on and off all day, I leave the cover off regardless, because the pool's there to use, of course. ;)