Help - solar cover = algae?

[Watermom]

I agree with John that one shock dose won't usually kill algae. But, there have been several people on the forum (including Poconos and me) that had some very slight issues with algae this winter when the water temp was below 50. (We used to tell people that below 50 they didn't have to worry about algae, but we found out that is not always true.)

Watermom

[HowardS]

I had this exact same problem 2 times last summer with my cover. I assumed that my cover itself was "contaminated" with with live algae after being off for a while, so that even though the pool itself was clean, it started to grow into the pool. And the pool gets much warmer with solar cover. (Your cover was new, so my theory doesn't seem to work so well.)

This year, I'm going to try to rinse off the cover really well before putting it on. I'll also not use the cover if the water gets to the high 80's.