FC/CYA/Temperature relationship?

[nefretrameses]

Florida. I have learned that my pool needs FC to be about 10% of CYA in summer to keep algae away. (FC=7 when CYA=70). If FC drops to 5 for even a few days, the pool starts to get a green tinge which I can quickly control. But now its October and the pool is about 10 degrees cooler. (I haven't measured the temp.) When I used a tri-chlor in-line feeder I dialed it back around this time of year.

My question is, should I expect to need a lower FC/CYA ratio with colder water to keep algae away? (My gut tells me that this is so). Of course there's also less sun on the pool and less of a bather load (which is always light). If I were to install solar heat, and raise the temperature back to where they were this summer will the FC/CYA ratio I need go back up?

[CarlD]

Your gut is right. Colder water inhibits algae growth. Here, up north, we expect when the water is below 60 deg there is very little algae growth, especially in a pool that was shocked just before closing. I frequently open in the spring to no algae at all.

[nefretrameses]

Thanks Carl. I let my FC drop to 5.0 for the past few days with no hint of green, but it made me a little nervous.