CYA gone but FC has been normal all winter.

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Poolmonkie

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Apr 28, 2017
57
Phoenix Arizona
I last tested my CYA one year ago in April, it showed 60 and has held at 60 since I started using the TFP method for 2 years now. I keep a very detailed log for my records and the FC has not been below 6 ppm at any time this past winter and usually I run it around 8 ppm during the hot Arizona summer.

I thought perhaps it was my test kit and tried it twice using older and newer chemicals, I also took a sample to the local pool chemical store and they verified CYA at 0.

I know it's common that if the FC reaches 0 during the winter that CYA is known to go to 0 but this is not the case with my pool. I will admit I have let the PH level rise above 8 most of the months that I haven't been swimming but otherwise we are very good about keeping the FC levels up.

Here is where I stand as far as levels:

FC 9.0
CH 600
CYA 0
TA 120
pH 7.6 (I just added MA yesterday but this is usually 8.0 during the winter and a constant battle to keep it at 7.6 all summer)

I was told at the store that the TDS was at 5000, not sure if that comes into play.

This water has been in for 2 years now and I have done nothing more than use liquid chlorine and muratic acid, no tablets or any other chemicals.

Any suggestions are certainly welcome, thank you.
 
Amazing. My CYA is consumed during the summer at a rate of about 10% per month.

I am surprised you CH is just 600 after two years.
 
Poolmonkie said:
I last tested my CYA one year ago in April, it showed 60 and has held at 60 since I started using the TFP method for 2 years now.
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I keep reading that statement over & over. That's unheard of. You sound very detailed about your chemical tests and recording, so I wouldn't jump to testing error conclusions, but that's really a new one to me.

Regardless, for it (CYA) to drop unexpectedly is odd. Do you have an autofill? Any chance you have a small leak which could account for the CYA loss?
 
Thanks for the quick replies.

I DID have a small leak in the auto leveler system that was fixed August of 2018, that leak might have been there for at least a year. So maybe that would account for the loss of CYA but it just didn't seem like it would have caused that much water loss and fresh replacement but I'm not an engineer, that is my uneducated opinion that the leak wasn't that much.
 
Poolmonkie said:
that is my uneducated opinion that the leak wasn't that much.
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That sounds like many of my opinions. :hammer: Still, you'd be surprised how much a small leak can influence chemical balance ..... AND your water bill.
 
As I understand it the CYA shouldn't really drop much unless there is a LOT of water being replaced, and I tested it twice in 2017 and once during 2018 and it has always been at 60. Again maybe the water loss due to the leak is the simple answer but wouldn't i have to lose a ton of water and wouldn't that be evident in my water usage?
 
CYA is degraded in higher water temperature. In my pool, in the summer, the temperature sits at or just under 90F. The CYA definitely degrades. I do not have a leak as my salt never changes.
 
I find it weird that the first summer I lost no CYA, but hey I will be the first to admit if I measured it wrong. I also checked my water usage for the past 2 years and I can't find anything that would suggest that the leak that was fixed was substantial. So that being said maybe I should just assume that I lost the CYA naturally through evaporation and replacement with the auto-leveler and I'm just sitting at 0 at this point.
 
You do not lose CYA via evaporation. In most areas of the country you are right, only way to lose it is with removal / exchange of water with fresh. But here were we have elevated water temperatures in the summer, there is some loss due to thermal degradation. Same thing happens in a spa.

I would not assume 0. Add 30 ppm worth and then test in a few days. You may have some, just under what you can test.
 

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the CH is the pool store test the rest are mine. I just did the CYA today using the TAYLOR test kit. I tested using chemicals that were 2 years old and also used some newer chemicals that were about 1 year old, so 3 tests were done on the CYA, 2 of mine and 1 of the pool stores. The only thing I know I didn't do right was getting the temp of the water up to room temp, it was most likely close to 60F at the most during the test. The last CYA test before today was April of last year and it showed a level of 60, this was again done by me using the Taylor kit.
 
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UPDATE: I ran the test again this time using the sample at 78F. I'm now reading about 30 ppm keeping in mind I just added 2 lbs of CYA stabilizer. I'll let the stabilizer continue to dissolve in the water for the next 24 hours and test again. Either way it looks like there is some CYA in the water at least.
 
30 seems more likely than 0 with small leak :)
Was the sample taken from the same area you put the CYA in? It usually takes 24+hrs for CYA to disperse, hoping it's a good sign for you!
 
1. That pool temp is not significant. The CYA test will be a little low in 40 degree water but will test just fine at 60 degrees.

2. Taylor will tell you your tests are invalid because your chemistry is expired (it's good for one year). Most of us know that if stored properly it will go longer, but you need ALL new chemistry so you can report your results with confidence

3. Adding 2 lbs of CYA gives you 15 ppm additional CYA in your pool. When did you add it?

TFPC is based on regular, precision testing. Going forward, you should get new chemistry and dedicate your self to testing pH and FC (and CC) and TA twice weekly.....many members test daily.

CH and CYA once each month. This regular testing will keep you tuned in to your pool and will detect any trends so you can make timely, small adjustments
 
It's been almost 24 hours since I added the stabilizer and myself and another observer both came up with a CYA of 40-45. This time I made sure that the temp of the sample was about 75 F and the chemicals I'm using are less than a year old from the test kit. Also all of my chemicals are stored in a cool dark temperature controlled area. The stabilizer was dispersed through the skimmer with quite a bit of it being pushed out into the deep end of the pool with none of it still existing after I ran the filter on high overnight for several hours.

I think I'm happy with the 45 for now and will monitor the chlorine consumption for the next week or two as the Arizona sun is slowly coming back and temps are rising into the low 80's for the first time this year. I think I would feel more comfortable running the CYA around 55 or 60 like I have in the past so I'll monitor the CYA in about a week and see if it has made a change and possibly slowly try to bring it up. In the heat of summer with the CYA at 60 I'm sometimes adding 128oz of chlorine a day to keep the FC near 7-8. If somebody would recommend that I leave it at 45 for the AZ summer let me know and I'll hold off on bringing it up in the future.

I am still a bit stumped as to how just over 24 hours ago I was showing 0 on the CYA after 2 tests and the pool store also showed 0, the only change was making sure the sample was room temp this time and the 2 lbs of stabilizer I added.

I keep a very detailed log and it goes back 2 years now, during the summer we are testing at least 3 times a week. The only one that I wasn't keeping a close eye on was the CYA since it never budged a bit. I'll make sure to check the CYA closer going forward.

Thanks for all the suggestions and help, if there is anything else you would recommend please let me know.
 
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Realize that a reading of 45 for CYA is not really possible. The scale on the vial is logarithmic. So we always recommend you round up to the next whole 10 -- for you that would be 50.

So the 2# of stabilizer added raised your CYA by 15 ppm. So your original level was at 30 ppm or so.

We also would suggest not adding dry CYA granules like that in the future. If they sit on the surface of the pool they can stain.
Add the CYA by using what we call the sock method. Get an old sock (no holes) and put the measured amount of CYA you need. Tie the sock closed and either suspend it in front of a return (hang it from your brush pole works with something weighted on the deck) OR if it still allows flow thru the skimmer, place the sock in the skimmer. Every 15/20 minutes give the sock a squeeze to speed up the process. Please DO NOT follow the directions on the container of CYA to just pour it into the skimmer and don't just toss the sock in the pool as the CYA is acidic and can bleach/stain pool finishes.
 

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