What's the most efficient CYA level? Also, is it better to add chlorine after sunset?

[nikon5400]

The lower CYA the more chlorine you need to add every day.

I've been using the same 12.5% chlorine for the last 4-5 seasons. I used to get by with 1/3 of a gallon, now I barely get by with 1/2 gallon. My CYA today is around 30-35, previous years was up to 60.

What are the disadvantageous of keeping CYA around 60? I noticed my pool getting bleached out a bit - could higher chlorine levels I had previous years contribute to that?


Another question - since my FC drops by .5 or less at night, does it make sense to add chlorine at sunset so the higher FC level stays throughout the night ?

Thanks.

 

[JasonLion]

The ideal CYA level varies a little bit depending on situation. For many pools it is around 50. If you have no shade at all, so sunlight shines on the water from dawn to dusk, then 60. If you have a SWG then 80.

Higher CYA levels make it more difficult to fight algae, should you get algae.

Liners bleach out over time regardless. Very high FC levels can slightly accelerate this process, but as long as you have any CYA at all, not by very much.

It is just slightly more efficient to add chlorine in the evening so it has more time to work before sunlight starts using it up.

 

[nikon5400]

Thanks Jason. Finally a good use for 5yr old tablets.