Solar cover and black-bottom IG pool

Our pool finish is a very dark Pebbletec (or something similar). On sunny days, the bottom and sides get quite warm, which is a nice built-in solar heating system. :D This will be our first winter (SFO bay area) with the pool and we want to try and keep it swimmable. (We have a gas heater, but I'd like to use it as seldom as possible.) So...

When looking at solar covers, would it make more sense to look at clear covers (if they exist EDIT: I've found a clear cover called Magni-Clear) and let the dark finish do its thing, or to get a regular old blue cover? I tend to think that letting the sun warm the sides and bottom thru a clear cover would be more effecient than would warming the water directly under the dark cover and keeping the sides/bottom cool. Does anyone have any first-hand experience with this?

Also, what is the general rule for solar covers? Do you want the cover off during the day if the air temp is going to get higher than the water temp? Or, will the pool heat up faster with the cover on all day?

Thanks.

Clear cover. Blue covers don't really warm the water, they help retain heat by (primarily) preventing evaporation. On warm days, you will actually get more heat in the pool by removing a blue cover. That supposed to be the main advantage of a clear cover, you can leave it on and the pool will gain heat.