i just got back from 8 days away with temps in the mid to high 20's everyday i was away. pool was covered with a solar cover for the whole period, timer was set for 2 -6 hour cycles each day,my normal. what i did was dumped in a full jug of chlorine night before i left then 2 pucks that morning (big round ones) when i came back saturday, i was very pleased how clean the pool was. i had some leaves on the bottom that came in around the edge of the cover, but the water was very clear. pucks were completely dissolved (so maybe 3 would have worked a touch better) and 2 very small streaks of algae. i vacuumed the pool, checked the chlorine and it was at a marginal level. dumped in a full jug of chlorine and the levels are great on all chems today. my cya level runs about 40ppm.