High CYA... so high FC so.... automatic cover OK?

[rigersa]

I have a CYA of ~100 and I know I need to eventually do some partial drain and fills. So I am keeping the FC in the 7ish range. Obviously that takes diligence with liquid chlorine. Anyway....

My question: Is that level of FC going to damage or prematurely degrade an automatic pool cover (model in my sig)? On windy days I would prefer to cover the pool to keep out dust and debris. I gather it is safe to swim in an FC 7 pool with high CYA from prior posts, but I can't find info on impacts to a pool cover. Their advice: "if it is safe to swim in, it is safe to cover." So is that true? Should I regard an FC level of 7 as equivalent to a safe swim level for purposes of the pool cover care?

 

[Griswald]

7 is not even a little bit high, nothing to worry about.

 

[rigersa]

7 is not even a little bit high, nothing to worry about.

Makes sense. Obviously I send it as high as 10 or 12 sometimes but I would imagine your statement still applies.

 

[DaninFLA]

7 is the bare minimum, you need to be much higher than that. to answer your question, 7 is completely safe, but it needs to be higher. a pool with CYA 100 and FC of 7 has less chlorine oxidizing power than a pool with 0 CYA and 1ppm. you need to get that FC up.

 

[chem geek]

The degradation rate of the cover is dependent on the active chlorine level which is the same at the same FC/CYA ratio. So 7 ppm FC with 100 ppm CYA is the same as around 2 ppm FC with 30 ppm CYA. It's roughly equivalent to 0.06 ppm FC with no CYA. So your cover should get degraded at the same rate as other pools at the minimum FC/CYA level.

People really need to stop thinking about FC alone as meaning anything with regard to chlorine's effects. By effects I mean the rate of disinfection, killing or preventing algae, or oxidation of pool covers, swimsuits, skin, hair, corrosion of metal, etc. The FC alone is completely and totally irrelevant. What matters is the active chlorine level and that is proportional to the FC/CYA ratio.

The only importance to the FC level is to tell you the amount of chlorine in reserve so that you don't run out. The only other time it is relevant is in drinking the water where the total chlorine capacity (FC) matters since it relates to total cumulative exposure when chlorine is used up rather quickly, but even here one would have to drink enormous amounts of pool water to be an issue and one should not normally be drinking pool water anyway.