I have a safety cover that is on all the time, except for when we are actually in the pool. As a family we have the process down pat to pull the cover back and to put it back on, so it is no big deal. Reason for our use of the safety cover year round is, well safety. Safety for the family, safety for the dog, safety for wild animals (got tired of finding rabbits, musk rats, gophers, etc. in the pool). We have trees all around, both conifers and deciduous. The safety cover does a great job of keeping needles, leaves, twigs, grass clippings, etc. out of the pool.
The previous safety cover we had was a standard duty, with a standard solid weave. Water easily drained through. It lasted 10 years.
Our current safety cover is 6 years old. It is a heavier duty than the previous. Almost no light at all passes through. Water will still drain through, but slowly. Actually had a problem towards the end of last summer where water would actually puddle in a couple of the center panels. I assume this was because very small leaf or dirt particulates clogged the tightly woven weave. Problem went away over the winter and no problem yet this year.
I attribute the safety cover to reduced chlorine usage, because of almost no light. Also no algae problem, probably a combination of no light and always good chlorine level maintained.
Not sure if a mesh panel is really needed.