Leslie's screwed up my CYA. Need to correct?

dooger54

Well-known member
Apr 21, 2017
81
Tucson AZ
#1
Another new user here after relying on Leslie's for testing and have them screw up. So here's what happened-

FYI. 10000 gallon Pebbletec pool with SWG.

I drained and refilled my pool back in January. I have been taking my water to Leslie's about once per week to get my water balanced, salt level correct, etc. They gave me my water balance report and luckily I kept them. The CYA level is the test that created my problems, following are the results and testing date. All tests done by them.

Feb 6 (soon after refill). CYA - 0. So of course they sold me stabilizer and I added the required amount.

March 13. (Probably had testing done before this but don't have report). CYA is now 40. Added recommended amount of stabilizer.

March 20. CYA is now 90.

April 4. CYA is now 70.

April 19. CYA now 40. So dumb me I add more stabilizer, not thinking to look back at my reports and see the bad numbers I have been getting. After getting on this forum and educating myself I now realize there would be no reason why CYA can go from 90 to 40 in one month.

April 22. Anxious to see if CYA good now. They tested - back up to 95!!

So at that point I got smart and ordered the Taylor 2006 test kit. I did my first test the other day and confirmed CYA is somewhere between 90-100.

So it seems my CYA now around 95. My questions-

Do I worry about this and do a partial drain?

I hate the idea of this since I just did a full drain in January. Or let it go since it is not a lot over the recommended 60-80 for a SWG pool? The pool is in Tucson, so with the heat this summer I am guessing I will get a decent amount of evaporation.

If I leave it at 94, what would be my recommended FC level to shoot for?

It is my understanding that higher levels of CYA require more FC.

Thanks!


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Richard320

TFP Expert
LifeTime Supporter
Jan 6, 2010
20,330
San Dimas, CA (LA County)
#2
Congratulations on getting off the pool store merry-go-round! :kim:

95 CYA is a bit high, but certainly manageable as long as you don't get algae. It's a shame you have a cartridge filter, otherwise backwashing would bring that down over time. CYA doesn't evaporate. Once it's there, figure it's going to stay there. The water evaporates but the CYA and CH stay behind. Which is why you'll see CH climb over time. But I digress...

If you go to poolmath and scroll down to the last row in the table where it says Suggested Goal Levels and select your parameters, it will automatically give you the suggested FC levels for your CYA. There is a whole lot of neat stuff within poolmath, so you'd do well to read Pool School - PoolMath before you just start plugging in numbers. You might miss out on some good stuff.
 

tim5055

Mod Squad
TFP Expert
LifeTime Supporter
May 11, 2014
10,096
Franklin, NC
#3
My first suggestion is to stop going to the pool store. Their only response it to sell you something.

Not much credence is given to pool store testing around here. While you would think that a "professional" would be the best, unfortunately in most cases it is quite the opposite. Between employees who blindly trust the word of chemical sales representatives and high school kids working in the pool store for the summer you end up with poor results from their testing.

There is no 95, if it's between 90 - 100 then count it as 100.

Your FC should be kept at 10-11 so it never drops below 7.

Evaporation does not reduce CYA, only water exchange removes it. When water goes away the other stuff in the water stays behind (CYA, CH and metals like iron/copper)
 
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dooger54

Well-known member
Apr 21, 2017
81
Tucson AZ
#4
So I went to Pool Math and input all my numbers. Tells me FC should be a minimum 5 with daily target 11-13. Was talking to pool guy the other day working on my neighbors pool, told him my FC was 6.5. He about flipped out, way to high according to him!

Anyway, I also retested my CYA 3 times today (new at this) and it for sure is 100, if not higher. If I want to get my pool down to 70 I'll need to take out about 3000 gallons.

Hate to do this since water is precious here in AZ desert, but might not be much choice.

Other numbers FYI-

Ph 7.6
FC 6.5
TA 90
Salt 3500
CSI -.67
CH 160



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Richard320

TFP Expert
LifeTime Supporter
Jan 6, 2010
20,330
San Dimas, CA (LA County)
#5
You did it right. The "pro" is sticking to the tired old nonsense that CYA number is unimportant and 3 is ideal for FC.

I used to keep my FC in the 20s the first year and I didn't suffer any eye irritation nor did my bathing suit bleach out or have the elastic disintegrate. The CYA buffers it. Think buffered aspirin -- it still works the same but it doesn't tear up your stomach. No difference. The FC still works but it doesn't attack everything. The downside to keeping it so high is that you are forced to use the FAS-DPD test every single time because the colorblock test doesn't read high enough.

Keeping low FC per the pool guy will only ensure that you need a weekly shock and/or buckets of yellow out and/or jugs of algaecide and/or phosphate removers and/or whatever else the pool store can unload on you. Stick with the poolmath levels and you will not see algae this season.
 

tim5055

Mod Squad
TFP Expert
LifeTime Supporter
May 11, 2014
10,096
Franklin, NC
#7
So if you were me, would you do a partial drain?
Is your water clear, no algae? If yes then I personally would work it down slowly. I took over my pool with a CYA of about 250 (CYA tests above 100 are just a guess, not very specific contrary to what the pool store says). With a CYA of 250 I had to keep my chlorine level at around 20 just to keep algae away. Through backwashes, small drain/refills and harvesting rain water from gutters I needed to add CYA this spring.
 

Richard320

TFP Expert
LifeTime Supporter
Jan 6, 2010
20,330
San Dimas, CA (LA County)
#8
So if you were me, would you do a partial drain?


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With what I know now, yes. I took over my pool with over 200 CYA and water restrictions in place so draining was out. I had to keep the FC above 20. It was still swimmable and I never got an algae bloom, but.... with the FC that high, the pH test was always suspect and I had to use the FAS-DPD test every time. No quick check with the color block for me. When I finally got CYA down to normal things were much easier. Even if you just get it down to 80-90, it will be an improvement. At least the CYA test will register somewhere on the viewtube.
 
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dooger54

Well-known member
Apr 21, 2017
81
Tucson AZ
#9
Is your water clear, no algae? If yes then I personally would work it down slowly. I took over my pool with a CYA of about 250 (CYA tests above 100 are just a guess, not very specific contrary to what the pool store says). With a CYA of 250 I had to keep my chlorine level at around 20 just to keep algae away. Through backwashes, small drain/refills and harvesting rain water from gutters I needed to add CYA this spring.
Never have seen a hint of algae in the 12 years we've had our pool.


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dooger54

Well-known member
Apr 21, 2017
81
Tucson AZ
#10
The other issue I have is we only winter here in Tucson. We will be leaving in about a week and my pool will be at the mercy of my pool guy. I'm not overly confident in his ability to monitor the FC.


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tim5055

Mod Squad
TFP Expert
LifeTime Supporter
May 11, 2014
10,096
Franklin, NC
#11
The other issue I have is we only winter here in Tucson. We will be leaving in about a week and my pool will be at the mercy of my pool guy. I'm not overly confident in his ability to monitor the FC.


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Generally they do not adhere to any of the methods taught here. They float pucks and shock weekly, meaning your CYA goes higher.