Does a pool cover change target values?


Well-known member
Feb 7, 2012
San Jose, CA
Has anyone thought through how a heavy-duty pool cover changes the target values that we should be shooting for?
For example, I'm imagining CYA should be lower than usual, since the water sees much less sun ...

TF-100 readings as of this morning:
FC 2.0 (added 1 gal after this reading, so probably around 5.0 now)
CC 0
pH 7.3
CYA 30
TA 220
CH 300?


LifeTime Supporter
Jun 6, 2013
I have a cover and still keep my CYA at 45ppm since when I do open it it doesn't deplete the FC during the day. The cover does save a ton of chlorine when it is closed. I will only burn about .5ppm per day when it closed verses about 2.5ppm per day if it is open.


Jul 8, 2014
I love our solar cover. I loose little to no chlorine when it is covered. I do have a smaller pool and add chlorine every 2-4 days to bring it up 1ppm when covered. It's wonderful, low maintenance and costs very little (thank you TPP!). I have averaged between 30-40 on my CYA this year. I just refilled after a new liner and fixing the pool. On a sunny day without the cover I will loose about 1 to 1.5 ppm (also dependent on swimmer load). I do agree with wjr75 about being closer to 40 for stabilizing. At 30 I think it is difficult (at least for me) to keep everything balanced and not drifting. When I approached 40 CYA everything pretty much stayed in target range and chlorine loses are minimal. I don't know enough about the chemistry to really give a legit response but just going by what I have noticed myself. I slowly brought up my CYA and my magic number was 35-40...A little tough to tell the number on my Taylor kit.

My normals:
pH = 7.4
FC = 3 to 4
TA = 110
CYA = 35-40
CH 150


Mod Squad
LifeTime Supporter
Jan 17, 2012
Evans, Georgia
If I'm not careful to open my pool up often enough my FC tends to rise more than necessary. I tend to run my CYA a skosh lower. My SWG is currently set at 10%.

Its good to open the pool and let the sun burn off any CCs and gas build up.


Well-known member
Sep 18, 2012
IL, NW of Chicago
Well now I'm curious. My CYA=40, and I target FC=7 (high end of min 3, target 5). I have a solar cover (temp ~89F now) and loose about 2-3 ppm/day with light load. Based on others experience, this now seems high. It has been like this all summer. Water is clear, and my pH tends to run low.


Bronze Supporter
TFP Guide
Jul 24, 2015
Central Valley CA
89F is fairly warm, the farther you go outside the range for your CYA the faster it will burn off cover or not, a clear cover will not protect as much as opaque, and 2-3 is normal I would not over think it. If the water is clear and has been all summer the only thing you should adjust is the amount of time you :paddle: more is always better.