FC with Solar Cover Considering CYA

[sparcel]

I’ve seen it recommended to keep FC under 2.5 to maximize the life of a solar cover. Is that as true when CYA is 50?

I’ve seen on TFP that with a CYA level of 50 I should not go below a FC of 3.75ppm (7.5% of cya). And I’ve seen on TFP that for swimming in a pool with cya of 50 that it is ok to have FC levels of say 5 or 6 that are not recommended by classic standards because the cya mitigates the impact on swimmers. Does cya also mitigate the impact of FC on the solar cover?

 

[YippeeSkippy]

Trust me, Sparcel....which ever pool store told you that is clueless to chemistry. Your CYA buffers the chlorine. So at a higher CYA level your FC needs to be higher also to be available to kill cooties. And solar covers only seem to last 2-3 years from the many folks here who use them. Don't overspend on one. It doesn't last any longer.

Here are some of our best quick reads-
ABCs of Pool Water Chemistry
FC/CYA Levels
Recommended Levels

We're happy you're here...and will help you all the way. But our best advice is "Stay outta da pool store!!"

Maddie

 

[sparcel]

When you say "which ever pool store told you that is clueless to chemistry", I assume you are referring to the limit of 2.5ppm FC to maximize life of the cover. If so, you could be right, though I have seen that guideline a few places, including Solar Covers - Does Color Matter?. Even more places, including the company that I bought my cover from say not to shock with the cover on. So I think it is reasonable to believe that some level of chlorine will impact cover life.

Indeed I know covers do not have long lives - though my last one lasted for 5 years. (What I dislike most about replacing my cover is the hassle of the work of trimming and attaching it to the reel.)

The core of my question is still whether the degree to which chlorine will impact my cover (or any other plastics) is reduced by the CYA level in the pool - similar to how it has been stated on TFP that CYA also reduces the impact of FC on the skin of swimmers.

 

[IceShadow]

Yes, it buffers the same way. See here:

CYA Chlorine Relationship - Further Reading

www.troublefreepool.com

The hypochlorous acid is probably what would damage a cover in too high a concentration, like the liner. Higher CYA buffers it and keeps that concentration down.

Pool stores, the liner manufacturer, equipment manufacturers, etc. all don’t recognize this relationship and so they give old limits for FC that are far lower than sanitary with CYA in the water.

 

[sparcel]

Thanks IceShadow. It would be great to know with a more certainty - but I suppose someone might need to do a long term empirical study on lots of pool covers, FC levels and CYA levels - which will never happen. You mention "like the liner". Has this relationship between FC, CYA and impact on liners been discussed somewhere that you are aware of?

 

[IceShadow]

Thanks IceShadow. It would be great to know with a more certainty - but I suppose someone might need to do a long term empirical study on lots of pool covers, FC levels and CYA levels - which will never happen. You mention "like the liner". Has this relationship between FC, CYA and impact on liners been discussed somewhere that you are aware of?

There are thousands and thousands of users here who have been following the methods for years and years. We would know if it bleached out and destroyed liners by now. Not much more thorough of a study you can do.

 

[sduda210]

I'm going on my third year with the same solar cover. I follow the salt water guidance with CYA of 80, FC target = 6 ppm. I am just starting to see a few bubble with water in them. I don't doubt I'll get thru this summer with it but I'll probably order a replacement for next summer. That matches the expectation of 2-3 years.

Would it be better if I kept my chlorine lowers lower? Maybe, but then I'd be in a constant cycling of shocking to kill outbreaks. As another data point, a coworker bought the same cover at the same time I got mine. A pool service treats his pool and the cover was done at the end of the first summer. That's a single data point so don't put too much faith in it.