Is it okay to keep the solar cover on all the time except when the pool is being used? Somebody told me that the cover should be removed at least every 3rd day to let the pool air out. I know that the sun lowers the level of free chlorine but aside from that I'm not sure of the effect of leaving the cover on all the time. I don't want to take the cover off more than necessary since it's extra work and keeps the pool warm.