Higher target CYA for Phoenix AZ ?

[cardano]

Hi Gang,
2 part question here : since I live in the Sun's Anvil ( Phoenix AZ ) should I be targeting a higher CYA level than 50 to combat the sunshine ( bleach not SWG ) ?

Currently I am between 55 and 60 on my CYA ( closest readings I can get since CYA test is the most subjective one out there )

Full readings :
FC 7
CC 0
PH 7.2
TA 120
CH 525
CYA 55-60

I figure that a CYA of 60 in Phoenix might not be a terribly bad thing, but have not been able to find anything other than the Pool School comment:

If you have a SWG or very high levels of direct sunlight, CYA is typically kept between 70 and 80.

Since I cannot imagine a place that has higher levels of direct sunlight, I'm guessing that my 60 CYA is just fine and I should not be looking to lower it as I had been. Similarly, however, it's probably not really worth taking effort to increase the CYA from 60 to 80 as I'll just be keeping a proportionately higher FC level than I already am.

Second question has to do with TA/CH/CSI, I've gotten My TA down from 190 to 120 but with my CH still up at 525, I'm still getting some scaling along the water line. I can continue to lower my TA but dont want to get it too low that I'll be swinging PH around alot, so I'm thinking of switching over to using a softened water line for my fill. Question here is : once I get my TA down to around 90, should I look at lowering my CH with soft-water to get my CSI level down? That assumes that CH can actually decrease like TA and not be just stuck like CYA. And embedded in that question would be : is my understanding that CH and TA kind of 'add' together to make CSI and increase the risk of scaling?

Thanks,
Cardano

 

[JasonLion]

Try out CYA where you have it now, and see how things go. Raising CYA a little more isn't out of the question, but doing so comes with some risks, so you don't want to go there unless the amount of chlorine you need to add really is an issue.

You need to keep CSI down to something reasonable one way or another. Topping of with softened water will certainly help, but it will also mean your softener uses more salt. Lowering TA will also help, and keeping a close eye on PH is also a good idea. You can use PoolMath to keep track of your CSI, and explore the different tradeoffs of the various approaches.

Quite a few factors affect CSI: PH, TA, and CH are the major ones, but water temperature, borates, salt, etc all contribute.