Went a little crazy with the CYA

klroahs

Active member
Jun 7, 2010
33
Huntsville, AL
Hello again,

In an effort to get my CYA up to 80, I used the pool calculator and added enough to get there (a little less, or so I thought). Now, my CYA is over 100 if my eyeballs are working properly. I did all this to try to maintain a higher FC value in my 95 degrees days with full sun.

How bad is it? I used the TF-100, and am not totally sure when the black dot disappears, but my wife has agreed with me so far. Not sure if one of the other tests may have a better method for measuring this accurately. I do not trust any result the pool stores tell me b/c on a recent visit my buddy and I split my water sample, and got completely different results. So...I don't know who to trust :)

The water does look clear, and I have just continued to add bleach to keep the Cl at a decent level, and from other posts this seems normal

30,000 Gallons
Pebble-Sheen pool
SWG
 

Richard320

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Jan 6, 2010
22,069
San Dimas, CA (LA County)
The biggest problem is that you won't be able to use the color matching test for FC, as you'll need to maintain higher levels than it can read with that high CYA.

If you used powder, it will probably keep climbing for a week, so take a measurement then. If liquid, you should be pretty close to whatever you read. As a check, you can try diluting your sample with 50% tap water (distilled, bottled, or filered water, in that order, would be better) then mix it with the CYA reagent and test again, then double your reading. Mix it well, take your readiung, pour it back in the mixing bottle, shake it some more, take another reading, and so on, until you're comfortable with the number you get.

Then you get to decide if a drain is in order or if you think you can live with it. If you have real high CH, draining might make more sense. Then again, you may be under water restrictions, like I am, and have to live with it a while. You can maintain a clear sparkling pool despite triple-digit CYA numbers, but I sure wish I could just grab a sample and compare colors.
 

klroahs

Active member
Jun 7, 2010
33
Huntsville, AL
It has been a week since I pulled the socks out, and I can live with it, and the water is clear and sparkling. I have left the chart range for the CYA/Chlorine, and cannot read the yellow color no matter what, so I pretty much use the drop test all the time. I am sure I am nowhere close to Cl level I am supposed to keep, according to that chart. However, that is another problem...

My CH is 230, which is in range for what Pebble sheen wants it to be. What are the problems with "living with it?" as opposed to draining. I have well water so I can refill if I must.
 

Richard320

TFP Expert
LifeTime Supporter
Jan 6, 2010
22,069
San Dimas, CA (LA County)
klroahs said:
My CH is 230, which is in range for what Pebble sheen wants it to be. What are the problems with "living with it?" as opposed to draining. I have well water so I can refill if I must.
You are experiencing one of them - the drop test for FC instead of a quick glance at the color block.

Another downside is should you get algae, you'll never be able to get FC high enough to shock and keep it there, short of contacting Chlorox and having them send a tanker truck out.

My pH readings are always suspect as well, although when it says I'm at 7.4 or 7.5, there's no eye or skin irritation nor dryness, and adding the prescribed amounts of acid has the expected result, so it seems right. Still, there's always going to be some nagging doubt that the pH test is way off because of the necessarily high FC.

And finally, you will constantly be having to explain yourself when you post that you maintain double digit FC levels.
 

klroahs

Active member
Jun 7, 2010
33
Huntsville, AL
About those double digit FC levels, my AquaPure documentation for my SWG says I should not go over 3.0 FC, which seems to match what I should have with the 70-80 CYA value except that my target should be 5. Seems like I have been adding Cl every couple of days, only to watch it drop and have to use bleach again (I thought more stablizer would help keep this a little more stable:). I guess I wonder how I can get algae if I have Cl levels well over 5?

Thanks for the help.
 

frustratedpoolmom

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In The Industry
May 20, 2007
12,226
SWSuburban Chicago, IL
It can happen - you need to do an overnight FC loss test with the SWG off. This test can only be done with the FAS-DPD chlorine test. Sounds like your SWG can't keep up with an unseen demand if you are having to add bleach and it's not maintaining the level.

Ignore the industry documentation - the industry hasn't kept up with scientific evidence that proves the old "1-3" FC recommendation ignores CYA and it's effect on FC levels... I'm not explaining that right. Where is Chem Geek! :mrgreen:
 

klroahs

Active member
Jun 7, 2010
33
Huntsville, AL
Thanks, Mom!

I am going to try an overnight test again tonight, but this time I plan on waking up before dawn...sigh...just in case, the other times I have tried this I saw no noticeable drop even after the sun had come up. It has been near 100 degrees here lately, and from other areas on this site, I have found that I might need to add some Cl when the temperatures are extreme.

My Jandy documentation warns to not go over 3.0 because of the risk of corrosion to my pump parts. I have read and understood (what I could :)) of the Chem Geek's post about the Cl to CYA relationship, but am wondering what the effect is on my equipment, that discussion does not come up in his posts.
 

JasonLion

TFP Expert
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May 7, 2007
37,880
Silver Spring, MD
The risk of corrosion from chlorine scales with the CYA level. The higher the CYA level, the higher your FC level can be without any risk of corrosion.
 

duraleigh

Admin
Mod Squad
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Apr 1, 2007
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Sebring, Florida
I think this thread points out how problematic it is to deal with CYA over 100......everything simply becomes more troublesome.

Rather than have all those issues (and assuming you have little to no iron in your well) why not partially drain and refill your pool and get your CYA down to around 70-80. There's no downside to that.

EVERYTHING gets simpler at that point.
 

JasonLion

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May 7, 2007
37,880
Silver Spring, MD
You should wait a week after adding CYA before measuring the level again. However, if you are doing a partial drain and refill, you can test the CYA level about an hour after the pool is refilled, leave the pump running during that hour to make sure the new water mixes throughly with the old water.