Questions on cya

[George Whitzel]

Not to question the experts on TFP but just trying to understand what is correct. I see on TFP that it is recommended that if you have a SWG your CYA level should be 70-80. Reading my SWG manual it states CYA should be in the range of 30-60. Why is there such a large difference between the two recommendations? My currrnt CYA reading is 60. Will i hurt my SWG if I bump my CYA up to 80?

 

[zea3]

It won't hurt your SWG at all. Since they are designed to put out small amounts of chlorine over a long period of time, we have found CYA levels of 60-80 provide adequate protection from UV rays for most pools, so that chlorine is available to oxidize organics throughout the day. With lower CYA levels, the small amounts of chlorine will burn off too quickly in the sun, and the SWG won't be able to keep up with demand.

The pool industry is just starting to acknowledge the CYA/Chlorine relationship and how they must be kept in ratio with each other, but they still don't quite get it. Most manually chlorinated pools will do fine in the 30-60 range as you are adding a large amount of chlorine all at once, and it will take time for the sun to burn it off. So now the industry is applying 30-60 as the standard for all pools regardless of how they are chlorinated.

 

[George Whitzel]

Thanks for the explanation! So since my CYA is at 60 I will be Ok but probably need to keep close tabs on my FC. I think I calculated using Pool Math that if I run my SWG 8 hours daily it will produce chloride gas equivalent to 3 FC so as long as the daily FC burn-off is not more than that It will maintain the pool FC level. I have been trying to establish that number as my SLAM is returning from shock level to normal range by measuring FC every evening at the same time. If I find that the daily FC burn-off rate is greater than 3 I will add conditioner to reduce the burn-off rate but will not exceed a CYA of 80. Does this sound OK?