Why different CYA Targets?

[Desterline]

I see the standard recommendation for pools being chlorinated "by hand" - manual additions of some type of liquid chlorine seems to be 50, though I've seen posts here giving that a range of 30-50 depending...
I also see that the recommended level with a salt system is a bit higher than that, 70-80 seems to come up a lot.

That's a pretty big difference - I'm wondering why?

I get that a salt system is a much more continuous process and _should_ maintain a more stable FC value, where a manual process is going to see a spike after the addition and a decline until the next addition. But in practice the salt system only gets run a few hours a day and the result is similarly uneven.

Anybody have a good explanation for the discrepancy?

-Denny

 

[jblizzle]

This has been answered many times over the years. The SWG adds FC very slowly and can benefit from the added protection from the sun. This also allows SWG to need to run less and prolong its life. The higher CYA is a balance between these benefits and the higher FC levels needed if a SLAM is required.

 

[timerguy]

The range of 30-50 is so you have a ballpark for what you want to target based on the amount of sunshine you get and your pool water temp. For AZ, I'd suggest your target should be 50. I'm running my SWG 12 hours /day now--just a tad over a few. And it keeps my FC replenished to my daily usage.

 

[Desterline]

The higher CYA is a balance between these benefits and the higher FC levels needed if a SLAM is required.

Ok, that makes a bit more sense as a risk/reward balance. On the risk side, needing to SLAM at the higher CYA levels takes _much_ more chlorine. But an automated chlorine system is less likely to "miss a day" and start a algae bloom. On the reward side there's less overall chlorine demand with the higher CYA level.

-Denny

 

[jblizzle]

Yup, that is a good summary.