Algae with solar cover on

[Frunobulax-]

I been using the TFP method for 6 years and have never had a problem. But it's been getting cooler here, and my pool has been covered most of the week. So, the past 2 weeks when I take the cover off I've had a layer of algae on the bottom.
I still tested it every other day or so with the cover on, and everything is fine. Salt pool with CYA about 70-80 and chlorine at 7-8ppm with no CC. I brush it down and it looks perfect after a couple hours of filtering. Just tested it this morning, same results.
The pool was absolutely perfect all summer with 0 issues. Can't figure why I'm getting algae.
Thanks.

 

[Bperry]

I been using the TFP method for 6 years and have never had a problem. But it's been getting cooler here, and my pool has been covered most of the week. So, the past 2 weeks when I take the cover off I've had a layer of algae on the bottom.
I still tested it every other day or so with the cover on, and everything is fine. Salt pool with CYA about 70-80 and chlorine at 7-8ppm with no CC. I brush it down and it looks perfect after a couple hours of filtering. Just tested it this morning, same results.
The pool was absolutely perfect all summer with 0 issues. Can't figure why I'm getting algae.
Thanks.

The cover probably has it on there.

 

[sande005]

Is it green? Or tan/brown? If your levels are as you say, I would tend to think dirt rather than algae. Pretty much why I gave up using a solar cover on my pool - it would accumulate all sorts of stuff that unavoidably gets washed into the pool when taking it off. Uncovered, whatever gets blown in gets incrementally removed by the filter, rather than being dumped in in one big slug.
If green and/or really algae, then I would spend time trying to figure out if the cover is interfering with the normal circulation of the water. Blocking a skimmer, outlets that hit the cover, and diminish the flow in a given direction, etc. increasing areas that don't mix with fresh incoming Cl very well, allowing growth in spots.

 

[Frunobulax-]

Is it green? Or tan/brown? If your levels are as you say, I would tend to think dirt rather than algae. Pretty much why I gave up using a solar cover on my pool - it would accumulate all sorts of stuff that unavoidably gets washed into the pool when taking it off. Uncovered, whatever gets blown in gets incrementally removed by the filter, rather than being dumped in in one big slug.
If green and/or really algae, then I would spend time trying to figure out if the cover is interfering with the normal circulation of the water. Blocking a skimmer, outlets that hit the cover, and diminish the flow in a given direction, etc. increasing areas that don't mix with fresh incoming Cl very well, allowing growth in spots.

Definitely green algae on a lot of the bottom (shallow and deep). All my returns are pointed up, for circulation, Maybe I'll try pointing them down with cover on. But I would think the main drain would pull enough water, to keep the chlorine homogenous.