Phoenix Arizona recommended CYA level

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beavis

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Jun 17, 2009
11
I am curious what the gurus on this board recommend for CYA levels in Phoenix. I have read in other threads that it should be somewhat higher than less sunny areas. My pool has minimal shade. Specific questions include:

1. What target number should I shoot for?
2. Since my pool is brand new and being filled with CYA zero water, is there really any point in testing CYA early on if I put the recommended amount in? i.e. if I know the volume of water and the number of pounds CYA, then the calculated concentration has to be correct, right???
3. Can someone confirm that I cannot use a standard chlorine test kit if my CYA level is high, because my FC will need to be over 5 and the standard FC test only goes up to 5?

Thanks!
 
You can use the FAS-DPD test to test above 5 (it tests up to 50) and it's contained in the TF100 test kit and the Taylor K2006. If you have a standard DPD chlorine test, you can use the dilution method to test up to 10 (although this is not as accurate). The typical yellow OTO test kit only tests total chlorine so isn't too useful anyway other than daily checks to make sure chlorine is present. (I can't distinguish between 3-5 on the scale anyway...)
I'd shoot for a CYA of 50-60.
No, you don't need to test new fill - tap water doesn't have CYA.
Use the Pool Calculator to determine how much CYA to add. :)
 
You can use the Pool Calculator to calculate the CYA levels for your pool. That will give you a target range. You could then introduce CYA so that it comes up to the high end of that range.

It is my understanding that CYA is somewhat of an illusive target; however, if you add the amount suggest by the pool calculator it should be close to the target level.

Standard chlorine tests only test to 5 ppm. I once had some strips that tested to 10. I have the TF-100 kit and use that now. The TF-100 will also test for CC (combined chlorine) which will tell you if you have organics that need to be dealt with. http://tftestkits.net/splash-page.html
 
Hey, beavis,

Back to yor first question.....in a manually chlorinated pool in AZ, I would suggest 50ppm as a starting point for your CYA. Get up and running keeping your FC around 3-5ppm.....not letting it dip below 3ppm.

If you lose around 2-3ppm daily over time (it'll take a week or more to figure out your daily loss) that's about as good as you'll get.
If you lose 3+ppm of FC, I would raise the CYA to 60 and see if it helps. I am reluctant to suggest over 60ppm CYA just because virtually everything about pool care gets harder with very high CYA....I hope 50 gets you losing 2-3ppm daily.
 
As Dave mentions, it gets more risky to manage a pool at higher CYA levels, mostly because if you ever let the Free Chlorine (FC) level get too low, the shock level is very high so takes a lot of chlorine to clear algae.

Nevertheless, there is a pool service in Arizona and surrounding states that uses 100 ppm CYA since they only visit the pools once a week and they raise the FC to 14 ppm when they visit and it drops to around 4 ppm when they come again the following week. So the loss is 16% per day (1.4 ppm FC per day on average, though more at first and less later in the week). They never get algae in any of their pools because the FC level is sufficiently high most of the time and the effective "shock" each week kills off anything that just gets started the last day or two. However, this is risky if one has unusually high bather load or organics get into the pool.

If you do need to go higher in CYA level, say to 80 ppm, then you can use 50 ppm Borates (see this post) as a supplemental weak algaecide which should at least take the edge off of any algae growth. Though that won't completely prevent algae if you forget to dose regularly, it should at least slow down the rate of developing a full-fledged bloom and let you battle any algae a little more effectively.

Richard
 
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