New SWG, conflicting advice about CYA

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L

lallyloo

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Jun 6, 2008
23
Montreal, QC
Hi, I've been reading the forum for the last week in order to get a handle on pool chemistry since we installed a new SWG. Its been a great resource!

Anyways, a little background we have a 58000 l inground fibre glass pool with sand filter, propane heater and (now) swimpure+ chlorinator. We bought the house at the end of August and had a hard time with the pool for Sept. and Oct. until we closed it for the winter. Hence, upon opening we had a SWG installed to ease our maintenance woes.

My confusion is this, the pool company who put in both the pool and installed the chlorinator AND the local pool store are pretty insistent that we don't need stabilizer. However, the swimpure+ manual AND everything I've read here says to add it.

I had the water tested at the pool store this morning:

Salt: 3000
FC: 2.5
pH: 7.4
TA: 90
CH: 250
CYA: 0

The SWG has been running for 3 days now and the water is clear. (temp 65-69F) We've also been running the pump 24hrs a day.

When I pressed the guy who did the test about why not to add stabilizer this is what he said: "You installed a salt pool so you wouldn't have chemicals in your pool, why add more. Also the stabilizer forms an oily film on the surface of the pool. Your chlorine level will be higher at night and go down in the day but you don't need a constant chlorine level and your water is clear so it's working."

Anyways, I still walked out of the store with 3.8 Kg of the stabilizer and plan to add about 3/4 to the skimmer this afternoon after a backwash on the filter.

Is there anything to what he was saying? I'm guessing they don't really understand how the SWG works and how I'll be seriously shortening the lifetime of my cell if I run w/o stabilizer.

Also how quickly will the pH go down and what should I do to counteract this?

Thanks for all advice!

Alison
 
You want CYA in the pool. Nothing about CYA has anything to do with an oily film. CYA doesn't ever cause an oily film. CYA will allow you to reduce the percentage on the SWG significantly. Without CYA you need to run the pump all day. With CYA you have much more flexibility in when to run the pump. An appropriately large SWG can work without CYA, but it uses up the cell more quickly and increases the odds of getting algae.
 
Thanks for the replies!

I added 1 tub (1.9 Kg) to the skimmer this afternoon. I decided to wait and have it tested next weekend just in case the concentration of this stuff is different than what is standard in the US. For dosage it says add 200 g per 10000 l pool, so it would mean 1.2 Kg for my 60000 l. Assuming its aiming for 30 ppm for a standard chlorinated pool, I'm pretty sure I haven't overshot my goal of 60-80.

As for the pH, it actually says on the tub that it won't affect pH, so I'll keep a close eye on it.

Alison
 
Hi, I'm just back from the the pool store with new test results.

Everything looks great:

Salt: 3120
FC: 3
pH: 7.6
TA: 120
CH: 220
CYA: 60

However, I got grief again (from a different guy) he wanted me to drain my pool to get the stabilizer down to 35. (Perhaps because on the results sheet it lists the desired range as 25-35 ppm.)

Now, I am convinced from everything I've read here and in my manual for my SWG that I do want the CYA at these levels in my pool.

I guess I need some reassurance that I CAN disregard what they're telling me!

So this is the story that I got today:

" Its too acidic it will cause problems with your children's eyes giving them ear infections and conjunctivitous, also it will ruin the heat exchanger on your heater putting copper in the pool and turn your son's blond hair green"

Now if the pH is 7.6 how can the CYA make the water acidic?

I have a Hayward H series propane heater that I think is supposed to have a cupro nickel heat exchanger, would this make it less likely to put copper into the water that a plain copper heat exchanger? Also , if the pH is 7.6 would the CYA still have an effect on the heat exchanger?

I'm going to try and convince my husband that its worth the $165 Can. to buy the T-K2006 so we won't have to deal with this every time we get want our water tested!

thanks for all opinions!

Alison
 
Wow, conjunctivitis from CYA. Thats a good one :lol: :)

Low FC levels are the only thing that might result in conjunctivitis. If anything to do with CYA relates to conjunctivitis, it would be low CYA levels. With low CYA levels, the SWG can't always maintain the proper FC level. Which could perhaps maybe lead to conjunctivitis.

CYA can lower the PH when it is added, but it is already added and your PH is just fine. Likewise, PH below 7.0 can damage your heat exchange coil, getting copper in the water and possibly turning blond hair green. But again, you know what your PH is and it is fine.

You have nothing to worry about, ignore what the store is telling you. The proper CYA level with a SWG is between 60 and 80.
 
lallyloo said:
Hi, I'm just back from the the pool store with new test results.

Everything looks great:

Salt: 3120
FC: 3
pH: 7.6
TA: 120
CH: 220
CYA: 60
Only thing I would do is lower your TA to about 70-90 ppm!
However, I got grief again (from a different guy) he wanted me to drain my pool to get the stabilizer down to 35. (Perhaps because on the results sheet it lists the desired range as 25-35 ppm.)
Exactly! Pool store employees are not that bright at times! (I can say stuff like this because I happen to work in a pool store!)
Now, I am convinced from everything I've read here and in my manual for my SWG that I do want the CYA at these levels in my pool.

I guess I need some reassurance that I CAN disregard what they're telling me!

So this is the story that I got today:

" Its too acidic it will cause problems with your children's eyes giving them ear infections and conjunctivitous, also it will ruin the heat exchanger on your heater putting copper in the pool and turn your son's blond hair green"
Nope, when it is in a chlorinated pool it forms chlorinated isocyanurates in the water and doesn't really exist in the acid form anymore!
Now if the pH is 7.6 how can the CYA make the water acidic?
It can't.....they just don't have a grasp on basic chemistry, pool or otherwise!
I have a Hayward H series propane heater that I think is supposed to have a cupro nickel heat exchanger, would this make it less likely to put copper into the water that a plain copper heat exchanger? Also , if the pH is 7.6 would the CYA still have an effect on the heat exchanger?
pH could have an effect on the heat exchanger,
CYA won't.
I'm going to try and convince my husband that its worth the $165 Can. to buy the T-K2006 so we won't have to deal with this every time we get want our water tested!

thanks for all opinions!

Alison
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lallyloo said:
I'm going to try and convince my husband that its worth the $165 Can. to buy the T-K2006 so we won't have to deal with this every time we get want our water tested!

Alison
Click to expand...

I just got my test kit from TF Test Kits by shipping it to a UPS Store in Detroit(I live near Windsor, ON). If you have some way of getting to a similar store just over the border, that would work. Or maybe a friend in the US that you can ship to. Figure I saved $80CAN AFTER tolls, parking and "hold for" fees. I got lucky and didn't get pulled in at the border for taxes either, so bonus for me this trip. PM me if you want more info,
 
The saga continues ....

So thanks for everyone's replies I was suitably satisfied that everything was good as far as the CYA was concerned in my pool. I was going past the pool store today after hitting the grocery store so I decided to drop in and get my water tested.

So today's numbers are:

Salt : 3000
FC : 5
pH : 7.5
TA : 110
CH : 240

CYA : 120 !!!!!! (a week and a half ago it was 60 which was a full week after it was added)


Now it was the same guy who tested it last time and he remembered me (unfortunately).

This is the story I got today:

"After 35 ppm of stabilizer in the pool it "makes itself" making the water more and more acidic, you have to drain the pool to get it down to 35 ppm."

Now the only thing I could think of when he told me this was that the guys at the forum are gonna love this!!!

The stuff I added was called Isocyanuric acid, it is the pool's stores own brand and no concentration is given. I've asked him twice if their stuff is industry standard and not some weird mutant form of the stuff, he says yes.

Now I've never used a test kit for CYA, but he showed me the test involving pulling a dipstick up a tube until a black dot appears clearly. From what I've read here, the test you guys talk about involves a black dot disappearing?

Now, nothing I've read here talks about this phenomenon of the CYA regenerating itself, and it really doesn't make sense. However, my pH is going down, it was 7.6 almost two weeks ago and 7.5 today, though I suppose that could be within the error of the test. Also, apparently my CYA is going up, though I'd be inclined to think that could be ascribed to a poorly performed test than anything else.

I know, I know I need to get my own test kit so I can be sure of my results, but I don't yet and I wanted to get some eye rolling reactions to my pool store experience!

One thing is sure that is if my CYA is 120 I am going to have to drain some water!!

So has anyone else heard of this runaway CYA regenerating reaction?

Thanks,

Alison
 
No but I have heard of inaccurate pool store test results which is what it sounds like what you have. The thing about CYA 'reproducing' above 35 ppm is pure BS (it's almost funny). Your pool store guy is, to put it bluntly, a jerk! (And I happen to be a pool store guy also!)
The dipstick test is a variation on the disappearing dot test. They basically work the same way.In one you pour solution into a view tube until the dot disappears. In the other you actually raise the dot in the tube via the dipstick untl it just appears. The results are basically the same. I would not stress over a pH change of .1 . that is really inconsequential.
 
Thanks waterbear,

Thing is I really don't see how I could have overdosed the pool with CYA , I put 1.9Kg tub into the skimmer which according to the Pool Calculator should only have raised the levels by 32 ppm.

So for now I'll put it down to 2 bad tests and eagerly wait to test it myself.

What is funny is that every time I've gone I've gotten a new "story" about stabilizer. As for the regenerating CYA story he told me so matter of factly like it was something they knew to be true.

I can see why they don't recommend that people put it in their pools, if they believe that's how it behaves!!!! Stabilizer that can go on a runaway regeneration reaction doesn't sound very stable at all!

Alison
 
How ironic...most pool stores around here tell you to not worry about your CYA level. CYA up to 200?? "Nah..don't worry about that...now, buy all of this shock and algaecide to kill off that algae and clear up your water...what?? didn't clear the water?? Why, then you need to buy lots more of this shock, and some clarifier..and oh yeah..how about some of this flocculant?? Yeah, you need flocculant!!".. :roll:

As waterbear has pointed out (and as several have attested to on here), most pool store employees really don't have a grasp of water chemistry and pool maintenance. They dutifully let the computer tell them what's wrong with your pool, and then start selling you all kinds of stuff you don't need. Of course, they're in the business of selling chemicals, too...hmmmmm..funny how that works out, huh? :wink:

So, either your pool store guy is either (a)completely misguided and misinformed, or (b) knows exactly what will happen if you don't add CYA to your pool (algae blooms and shortened SWG cell life). Either one isn't appealing.
 
Re: New SWG, conflicting advice about CYA **Update my test #'s

Hello again everyone,

Well I finally got a test kit of my very own today :-D

These are my numbers from today:


FC : 2.2
CC : 0.2
pH : 7.6
TA: 100
CH: 250

CYA: 30 (although I wouldn't say that the dot had completely disappeared)

According to the PoolCalculator what I added to the pool (1.9 Kg) should have raised the CYA by 32, so the number I got by performing my own test makes complete sense.

What the guy at the pool store was telling me did not make ANY sense! I can only think that they are just performing the test wrong either by adding the wrong amount of reagent or reading their dip stick test wrong. Funny thing is that I went to a different location of the same chain and was told that the stabilizer was somewhere between 80 and 100. So whoever is training these guys or writing their procedure manuals is completely out to lunch!

Now, instead of worrying about too much stabilizer, I have to add some more. I have another 1.9 Kg tub, I was thinking of adding half and retesting in a week. It freaks my out a little adding more after being told I had a CYA of 120 but, I think I need to pretend that I never had my water tested by them and carry on with the original plan.

On an interesting side note, the guy that told my that my CYA was 120 told me to turn off my pump so that stabilizer would all rise and then drain from the top. He even had a neato diagram showing how to connect the vacuum hose to a floating coat hanger so I could skim all the stabilizer rich water from the top of my pool! Now, doesn't that violate some law of thermodynamics? If something is in solution it stays in solution unless precipitated out by evaporation. They seem to think that is an oily substance that is in an unstable dispersion hence the comment about forming an oily film on the surface.

Anyways, I'm so happy to have control over my own test results and I wanted to share the (hopefully) end of the CYA saga.

Alison
 
Re: New SWG, conflicting advice about CYA **Update my test #'s

lallyloo said:
On an interesting side note, the guy that told my that my CYA was 120 told me to turn off my pump so that stabilizer would all rise and then drain from the top. He even had a neato diagram showing how to connect the vacuum hose to a floating coat hanger so I could skim all the stabilizer rich water from the top of my pool! Now, doesn't that violate some law of thermodynamics? If something is in solution it stays in solution unless precipitated out by evaporation. They seem to think that is an oily substance that is in an unstable dispersion hence the comment about forming an oily film on the surface.
Click to expand...
Your analysis is essentially correct. They say that a little knowledge is a dangerous thing, but I think it's powerful. CYA isn't a substance that stays separated from water such as oil. It's more like salt that dissociates into ions that remain in solution. Some CYA doesn't dissociate, but is polar enough (in local regions of the molecule) to stay dissolved in water.
 
Thanks chemgeek!

My Ph.D is in physics not chemistry (seriously)! So I tend to have more of a generalist's understanding of chemistry. The thing I never really liked about chemistry was that every molecule can behave differently because of its unique structure and environment.

Now, if only we could impart just a little knowledge to the guys doing the tests over at my local pool store!

Alison
 
These are my numbers from today:


FC : 2.2
CC : 0.2
pH : 7.6
TA: 100
CH: 250

CYA: 30 (although I wouldn't say that the dot had completely disappeared)
Click to expand...

I'm still learning too, but with CC's doesn't the FC need to come up to 'shock level' to clear it out? And TA should be a little lower 70-90 for a SWG pool?
 
lallyloo said:
Thanks chemgeek!

My Ph.D is in physics not chemistry (seriously)! So I tend to have more of a generalist's understanding of chemistry. The thing I never really liked about chemistry was that every molecule can behave differently because of its unique structure and environment.

Now, if only we could impart just a little knowledge to the guys doing the tests over at my local pool store!

Alison
Click to expand...
Alison,

Just for the record, I'm not a chemist, don't have a PhD in chemistry, don't work in the pool/spa or even chemical industry. I majored in physics and chemistry at Cal Berkeley (they didn't allow for a double major due to too many overlapping course requirements so technically it's a field major in physical sciences), but ended up working in computer software development/management. I do have an (obviously) strong interest in pool water chemistry ever since I ran into problems using Trichlor in my own pool 4-5 years ago and got virtually no qualified help from the pool store.

I don't really blame the pool store employees since they are just told things by the manufacturer reps, literature, and water testing programs that they use. If anyone is responsible for the lack of understanding in this industry, it is those who have the knowledge of the chemistry that intentionally withhold it for whatever reason. I'm hopeful that some day these people will snap their fingers when they wake up in the morning and ask themselves "what can I do today that will help people?", but then I'm an optimist. :-D

Richard
 

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