CYA for Salt Chlorinator Pools...

[waterbear]

Here is the CYA article about plaster and CYA:

http://findarticles.com/p/articles/m...4/ai_n15932555

Although this probably applys more to very high CYA, this was why I was reluctant to go to higher CYA levels. I may end up going a bit higher anyway.

The sudy was done by ARCH chemicals! These are the same people who put copper into trichlor pucks. I am sure they are talking about CYA levels well above 100 ppm! There is also evidence that sulfates from using dry acid can affect the plaster so there can be multiple causes for damage to the plaster finish. The article did state that ARCH chemical recommeded switching between trichlor and other forms of chlorine to keep stabilzier levels from going too high. Does this mean that they are starting to read the Pool Forum? Seem like THAT piece of advice has been given on here for a very long time!

[dep78737]

Looks like the SWG manufacturers understand their products better than we do. It's in their best interest to suggest CYA/CL levels that will work in a vast majority of pools, otherwise people would be cursing them instead of singing their praises. Partially based on advice in this forum, my CYA was around 40 last year and I kept having to crank up the output. Raised it to 60 this year and now run at 40-50% instead of 60-70%. FC levels are more stable and acid use is down also, maybe since it's working less and maybe since the plaster is now 2 yrs old.

[waterbear]

If your cell output is down your pH should not drift up as quickly since you are manufacturing less sodium hydroxide! Another reason to run the cya a little higher! Actually, your results are pretty typical of the things I have seen with my customers when viewing their histories. The vast majority of them bring water in for testing weekly or bi weekly and the LaMotte software we use allows me to graph test results which makes spotting these trends easy to see. (Now you all know what I do when I get bored at work!)

[bbb]

Great thread - thanks to everyone posting.

For what it's worth - I'm on my first year with a Pool Pilot, and *have* been able to keep FC in the pool even with CYA in the 30 range (28K gallon pool, 48 size cell, power level 2, 20% to 33% usage). I have been debating about where to keep my CYA levels, too. I have kept my new solar cover on at all times this year except for when we actually are using the pool. One theory is that my blue/silver solar cover has helped me maintain a higher FC level in the pool, since there is less sunlight hitting the water. I chose blue/silver because I wanted to preserve heat from my heat pump.

However, thanks to all these discussions, and the fact that we are now in full summer "school is out" mode - meaning more time with the cover off and a higher bather load) I bought 2 bottles of hth brand CYA at my local hardware store to raise the level to around 50-60. Interestingly, the hth bottle is starting to warn people of CYA levels -- it says 20-40 is ideal, and it also says that chlorine effectiveness is severely limited over 100.

One other boast - I used plenty of borax to stabilize my ph last year, and added more this spring. My ph has been constant at 7.2 all year! My theory - lots and lots of acidic rain in the Northeast this year. So I expect the ph to eventually drift up -- although we have rain in the forecast for each of the next 7 days...

Related boast - between the rain and the solar cover, I have not added one drop of water to the pool - on the contrary, I have had to drain inches off several times!

Final boast - 2nd year of bbb, perfect water every day this year - nothing added to pool except bleach (pre-SWG), polyquat (early spring, to make sure no algae before the cover came off), baking soda (to bring my alk up in early spring), and borax (pre-SWG, to bring ph up to 7.4, though it never moved)

last reading:
FC 3
CC 0
CYA 30 (will raise to around 60 for SWG, but no worries)
TA 90 (may raise with some baking soda, but no worries)
ph 7.2
salt 4400 ppm (overcalculated when I added it for the SWG; no worries)
calcium - doesn't matter - vinyl pool with titanium core heater

[mas985]

Ok, I think I am convinced. I will try a CYA level closer to 60 ppm. It will be interesting to see how much the CL level rises with a CYA rise.

[mas985]

Last week I raised my CYA from 30 to about 55. After a week of running with the higher CYA, I have come to the conclusion that it had no affect on my residual chlorine level. During this week I did not change my pump run time or the chlorinator setting. Also, pool temp and PH where about the same.

CL = 2 ppm @ CYA 30 ppm
CL = 2 ppm @ CYA 55 ppm

So the graphs from the CYA study are correct in that chlorine retention does not increase significantly for CYA levels more than 25 ppm even for a SWG pool.

One other question. Assuming the same residual, is a SWG any different than an ORP controller with liquid chlorine? Both would need to add chlorine to the pool at the same rate for the same residual. To me at least, once you get past the chlorine injection method, there is no difference. Therefore, why should the CYA levels be any different? Also, the argument about shocking in the cell for SWGs also applies to the liquid chlorine. The chlorine concentrations would be just as high near the injection point.

Sorry for keeping the debate going but there seems to be a lot of conflicting information, theories and experimental results.

[PoolDoc]

Hi All;

This thread had become both extremely long, and overwhelmingly complex. Consequently, I moved the *full* version to the China Shop. Contrary to what some seem to think, this does NOT mean I disapprove of the thread; rather I just think the thread is too long and too complex to be helpful to newbies.

The full thread is here, CYA for Salt Chlorinator Pools II .

Please continue the debate there. This especially means you, Waterbear, Waste and Chem Geek!

I'm going to summarize some of the less controversial bits below.

Ben
"PoolDoc"

[PoolDoc]

Well, I would've summarized the bits below, but the power went off, and my UPS ran out before I could save the work I'd done. Guess I need to replace the battery.

It's back on, now (finally). But, I gotta go.

Maybe tonight.

Ben

[waterbear]

Looking forward to the summary....lot's of good info got exchanged in this thread and once it is sorted out should be very useful!