CYA for Salt Chlorinator Pools...

[Karin]

Hi folks....I'm new, but eager to be part of this 'wet ' wild' pool community. ;)

My present concern is about the best CYA level to maintain for a pool using an Aqua Rite Salt Chlorinator. I recently drained and refilled some of my pool in order to reduce the CYA from 100ppm to about 40ppm. I would really like to stay in this range, but for some reason the manual suggests 60-80ppm.

Does anyone else have a SWG system and what do you keep your CYA at? Why would a salt system need higher CYA?

Thanks in advance. Karin

[tonyl]

The higher CYA helps the chlorine stick around in your pool longer. That allows you to run with a lower output setting on the SWG. I've had one for several years with cya of 70-80 and 1-2ppm chlorine with great results. I only add bleach after very heavy rains. Hope this helps, Tony

[Karin]

Thanks Tony....that does help. How long do you run your SWCG each day? It seems that mine is way too eager to please and my chlorine level is up at 6ppm after running the pump/filter/Kreepy thing for about 6-8 hours each day.

I know I can adjust it downward and I do....but we just had a horrifying experience with yellow algae and now I'm nervous that the alien algae will return.

[gwrace1]

I run my CYA at 35-40PPM with a FC level of 2.5 PPM. Aquarite is set on 40% and runs for 12 hours each night with pump on low speed. Water is always crystal clear.

[tonyl]

Well for our pool my output is up a bit this year due to the hot hot summer so far here in the midwest. I'm at 50% and 8 hours per day. Water temp is 91.

Edit: forgot to mention it's more efficient to run with salt at the higher end (3400), your output is also dependent on the salt level.

[rbonin]

The high recommended CYA level by most salt water chlorinator manufacturers seems to be a mystery to most on this forum.

I abide by Ben's "best guess" chart of CYA vs. FC and so I keep my pool at 40ppm CYA and about 5ppm FC. My Polaris AquaClear cell runs 10 hours a day as my pool is in direct sun all day.

[mas985]

I am interested in everyone's settings as well, since there seem to be many different lines of thinking on this:

1) Use recommended CYA 60-80 and keep chlorine level per Ben's CYA table.
2) Use recommended CYA 60-80 and ignore Ben's CYA table and rely on cell to continuously shock water plus add bleach when necessary.
3) Use lower CYA level and Ben's CYA table. Recent studies indicate the CYA can contribute to dissolving plaster and shortening it's life.
4) Use lower CYA level, ignore Ben's CYA table and rely on cell to shock water.

My current preference is #4 since I have a plaster pool and not quite at Ben's CL ppm. I am operating at a CYA of 30, 21000 gallon pool, setting 90% and run the pump 6 hours a day. I am able to maintain 2 ppm. I have calculated that with my current settings, the cell puts in about 2 ppm per day so I figure I am using up 2 ppm per day.

If anyone is interested, the aquarite/logic cell puts in 1.45 lbs/day @ 100% setting. This is equivalent to 1.45 gallons of 12.5% bleach.

I think if I upped the CYA with the current settings, the chlorine would probably rise but not as quickly as per Ben's table. I am trying to research this a bit more to see if I can predict a chlorine ppm level with different CYA levels. I would love to experment with different CYA levels but given the difficulty of reducing CYA, this is not an option.

[cwstnsko]

Agree with the previous post about following Ben's guidelines. I run my CYA at about 30 ppm. I adjust the SWG so that my FC is at about 5 ppm in the morning, and it drops no lower than 3 ppm by late afternoon in full AZ sun. I run my pump on low speed 24/7, SWG at about 30% on power level 1, salt is at 2900-3000.

[Karin]

I've heard that using my SWCG to shock will hasten the cell's life expectancy. I don't want to hasten its demise and will probably use good ole bleach on the occasions it may need some shocking--after heavy rains.

I can only run my pump at one speed. It can adequately turn my water in a 4-6 hour period, but I leave it on for 6-8 hours....it usually starts at 8am. Should I maybe have it start later in the morning so that it runs during most of the hot afternoon part of the day and keeps adding fresh chlorine that way?

Based on your comments, I'm leaning toward a CYA of around 50---close to Ben's recommendations and also Aqua Rite's. How's that for straddlin' the fence?

Tell me more about CYA staining??? I added some the other day through the skimmer---tried to dissolve it with some warm water first, but that stuff doesn't like to dissolve, and then slowly poured it into the skimmer while it gulped it down.

I presently have some yellowish stains in corners and the risers of the steps and along the walls in the deep end that appear to be recent. Since we just had it resurfaced with some Diamond Brite in March, I'm very concerned.

We had a bout of yellow algae about a week ago---which I think is gone. (Cleaned the filter daily.)
We did a partial water change to lower the CYA only to find out that the city water was full of phospates....plus I forgot to add a sequestering agent till after it had been filled. Then after going to 4 pool stores and getting 4 different CYA readings of : 15, 25, 30 and 60 all from the same sample, I added some CYA to bring it up to 40. Yes....I do need a life...

So now I'm wondering what the culprit is for the stains:

From the Yellow algae?
From the new water full of phosphates etc?
From the additional CYA?

Other than for the stains, the pool and water look great: clear and blue....sigh..I should be in there right now instead of typing about it....
FC 6.5
TC 6.5
PH 7.4
Hardness 200ppm
Alkalinity 100
CYA 40
Salt 3100

[Simmons99]

I've never heard of CYA staining - it could be due to metals or algae

[PatL34]

Karin & Others,

The 60 - 80 ppm CYA recommended by the SWCG manufacturers is because the cell instantaneously creates a high concentration of chlorine, and kills the chloramines as well.

Without the high CYA, the chlorine would be used up rapidly before it gets into the body of the pool.

With my SWCG, a 50 - 60 ppm CYA level appears to work fine. So 50 ppm you are using is in the ballpark.

Regarding the staining, it could well come from your fill water, but others with more experience can help you. Have you tried to brush this stain? To my knowledge CYA does not stain, otherwise we would be using something else.

Your water chemistry apart from the CYA is also in the ballpark, and I can well understand your frustration with 4 pool stores giving you different readings, so I take them with a pinch of salt (pun intended);) They do not know how to be consistent. Once you do it yourself the same identical way each time, you will be less frustrated:D

mas985, I would use option #2, based on what I said at the beginning. The cell should produce the chlorine regardless, and if not you can always aise the output. A bit of trial & error. I have not heard of CYA dissolving plaster pools. That's a new one to me. Will have to investigate.

Hope this helps.

Pat

[Karin]

Well, I went to the horse's mouth and called up Aqua Rite to ask them about their higher recommended CYA levels. After 10 minutes of listening to some vintage elevator music, the rep told me that the chlorine that a SWCG makes is different than the regular chlorine you just add to a pool.

That's why they want a higher CYA---to protect it from sunburn.

Was she just trying to get me to hang up, or does that sound plausible? Hmmm...

[tonyl]

I think you'll have to experiment a bit on your CYA levels. I keep mine within the recommended range due to full sun exposure. I think most pools would be fine with 50ppm and after all, stabilizer isn't cheap.

[waterbear]

Well, I went to the horse's mouth and called up Aqua Rite to ask them about their higher recommended CYA levels. After 10 minutes of listening to some vintage elevator music, the rep told me that the chlorine that a SWCG makes is different than the regular chlorine you just add to a pool.

That's why they want a higher CYA---to protect it from sunburn.

Was she just trying to get me to hang up, or does that sound plausible? Hmmm...
She told you the same thing that PatL34 stated above and the same thing that I have stated in other threads. There is a difference between manually chlorinating and producing chlorine by electrolysis. I have spoken to tech support at Goldline Controls, Poolsean, who is in this forum and works for AutoPilot Systems (Pool Pilot SWG's), and some of the dealer literature that I have access to from my job (the store I work at sell several brands of SWGs) all are saying the same thing. It is better to run the CYA level higher in a pool with a SWG. I run mine at 70 ppm with my Aqualogic PS-8 (Goldline Controls). I also test a lot of water all day and can access histories of test results. About half our customers have SWG's installed and there are several that have been running CYA at 30-50 ppm. I have notices that these people have not been able to maintain adequite FC levels, run their cells at very high outputs, and some have had problems with algae blooms, including Mustard Algae. I have not seen any of these problems in the ones running higher CYA levels and keeping the FC at about 3 ppm or slightly higher. It is a small sample, maybe about 50 or 60 customers but the trend I have seen is unmistakable!

[mas985]

Here is the CYA article about plaster and CYA:

http://findarticles.com/p/articles/mi_m0NTB/is_23_44/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.

[waterbear]

Here is the CYA article about plaster and CYA:

http://findarticles.com/p/articles/mi_m0NTB/is_23_44/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!:D

[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 (http://www.poolforum.com/pf2/showthread.php?t=4495) .

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!;)