Thanks for the update! In my opinion your CYA is too high as your CYA gets higher it starts to render your chlorine ineffective, here is a useful chart showing the relationship between your CYA and Free Chlorine.
The bad thing about lowering CYA is that it can only be done by draining your pool and re-filling with fresh water. If you do decide to drain your pool and refill with fresh water then I would hold off on shocking until you drain, re-fill and re-test your CYA. If your pool is a non-salt water pool then the ideal range for your CYA is between 30-40 PPM.
Your CYA can get high from Chlorine Tablets as chlorine tablets are called Stabilized Chlorine meaning that the tablets release a small amount of CYA into the pool, over a long period of time (i.e. a pool season), your CYA will gradually increase from the slow release of CYA from the chlorine tablets. One of the benefits of using liquid chlorine is that it does not have CYA in it so the liquid chlorine will not increase your CYA.
Tell me what you think about this idea. Sounds like the high CYA levels could be having some effect on my chlorine readings. The only way to get that down is to partially drain and refill the pool. Given the fact that the water is very clear and no sign of alge, and I’m getting ready to drain the pool past the return for winter anyway, what do you think about hitting it with one of your closing kits, draining it down and covering it for the winter. Then work at CYA, chlorine and PH levels in the spring.
Seems like an awful wast of time (and water costs) to drain, fill and drain again.
I am sure that Patrick would agree that the partial drain and winter closing kit would be a great choice. Just remember that when you open the pool and have added fresh water, check the CYA levels at that time. You may need to do an additional partial drain and refill if your CYA level is not in the recommend 30-40ppm range.
Thanks guys! That’s the answer I was hoping to hear. Two more quick questions for you then I’ll leave you alone.
I have a looplock mesh winter cover. Even though I drain the pool below the returns, by spring the snow melt has filled the pool to the top. Does snow melt (and rain for that matter) contribute to the high CYA levels? Normally I just work to clear the water in the spring without draining it down. With the problems I’ve having, next spring I will drain it down and refill.
Secondly, with my chlorine and CYA issues, is there a particular closing kit you carry that you would recommend?
The snow melt and rain water will only contribute to dilute and lower the CYA levels, as fresh water is the only real way to reduce the CYA levels.
As far as a winterizing kit, I would steer clear of the DI-chlor chlorine kits as Di-chlor will only increase your CYA levels. I would recommend the 15,000 Gal. Winterizing Kit W/ Chlor-Free Shock. If you want to add chlorine in some form, I would recommend purchasing Super Zappit (73% Cal. Hypo.) for shocking. This product will not increase your CYA levels. You can also use Liquid Chlorine if you would like.