Trouble with CYA test

[michacunique]

My pool currently has an algae problem. I got my water tested at Leslie's, did some research and ended up here. At this point I zeroed in on results from the pool store that had my CYA level at 130. After further investigation this high level seemed to make sense, because I had been chlorinating my pool almost exclusively with dichlor 'shock' and trichlor tabs on the advice of said store. I decided on a plan of action:

1. get a decent test kit for SLAMing
2. drain pool as necessary to get CYA to a reasonable level
3. SLAM
4. Attempt to maintain chlorine levels with some tabs and liquid chlorine (or bleach) to prevent extreme CYA buildup in future.

The original Leslies test was on 7/13. Between vacations and just trying to let the temperatures cool a little here in Phoenix, I am just now getting to this process. My K-2006 kit showed up, and I went ahead and tried out the CYA test in the kit, this is the one where you add the cloudy solution until you can't see the black dot at the bottom of the container. I tried the test the first time with a 50% dilution (3.5ml pool and 3.5 ml tap water) assuming my value would be off the scale, but instead the water wasn't cloudy at all. I was able to fill the thing up and easily see the black dot. I tried again with the full 7ml of pool water and this time the water was slightly cloudy but I could still clearly make out the black dot when the vial was full. I was planning on draining my pool tomorrow (we have some cloudy weather forecast for the week), but now I'm just full of questions.

- I tested in the evening after the pool had been stagnant for 11 or so hours (it runs at night). Is this a problem? If it was I would hope the manual or test instructions would mention it.
- It isn't possible for CYA to go down like this on it's own, right? The test kit book says the only way it will go down is with splashing, backwash or draining the pool. I don't backwash since I have cartridge filters.
- I'm willing to entertain the idea the pool store was off, but their number makes more sense than mine given the stabilized chlorine I've been using.
- I got two bottles of the R-0013 with the kit, and I tried a different one for each test. They're within their printed expiration dates. Is it possible both are bad?
- I'd love to get another data point, but where? Is Leslies or another pool store too unreliable? I'd hate to have to order and wait for another test kit.
- I got this kit from Amazon, is there a more reliable place to get kits?

Thanks for any help you can offer!
Mike

 

[jblizzle]

This is why we do not trust pool store testing. Sounds like your CYA is not very high at all.

No way to know how old that kit is or how it was stored. That is why we highly recommend tftestkits.net

Wait are you saying the high CYA result was 2 months ago and you never tested again until now?

 

[cjpwalker]

How are you performing the test?

-Hold the tube at waist level, standing with your back to the sun, and look straight down from the top as you add the mixture...

 

[domct203]

My pool currently has an algae problem. I got my water tested at Leslie's, did some research and ended up here. At this point I zeroed in on results from the pool store that had my CYA level at 130. After further investigation this high level seemed to make sense, because I had been chlorinating my pool almost exclusively with dichlor 'shock' and trichlor tabs on the advice of said store. I decided on a plan of action:

1. get a decent test kit for SLAMing
2. drain pool as necessary to get CYA to a reasonable level
3. SLAM
4. Attempt to maintain chlorine levels with some tabs and liquid chlorine (or bleach) to prevent extreme CYA buildup in future.

The original Leslies test was on 7/13. Between vacations and just trying to let the temperatures cool a little here in Phoenix, I am just now getting to this process. My K-2006 kit showed up, and I went ahead and tried out the CYA test in the kit, this is the one where you add the cloudy solution until you can't see the black dot at the bottom of the container. I tried the test the first time with a 50% dilution (3.5ml pool and 3.5 ml tap water) assuming my value would be off the scale, but instead the water wasn't cloudy at all. I was able to fill the thing up and easily see the black dot. I tried again with the full 7ml of pool water and this time the water was slightly cloudy but I could still clearly make out the black dot when the vial was full. I was planning on draining my pool tomorrow (we have some cloudy weather forecast for the week), but now I'm just full of questions.

- I tested in the evening after the pool had been stagnant for 11 or so hours (it runs at night). Is this a problem? If it was I would hope the manual or test instructions would mention it.
- It isn't possible for CYA to go down like this on it's own, right? The test kit book says the only way it will go down is with splashing, backwash or draining the pool. I don't backwash since I have cartridge filters.
- I'm willing to entertain the idea the pool store was off, but their number makes more sense than mine given the stabilized chlorine I've been using.
- I got two bottles of the R-0013 with the kit, and I tried a different one for each test. They're within their printed expiration dates. Is it possible both are bad?
- I'd love to get another data point, but where? Is Leslies or another pool store too unreliable? I'd hate to have to order and wait for another test kit.
- I got this kit from Amazon, is there a more reliable place to get kits?

Thanks for any help you can offer!
Mike

Welcome to the forum.

You said you tested CYA in the evening, this will give a false result, as well as checking indoors.

You need to check CYA outdoors on a bright sunny day, with your back to the sun as mentioned.

How long have you been chlorinating with dichlor & trichlor?

 

[AUSpool]

Hi Mike and again welcome to the forum,
of all the tests the CYA is the most subjective, for me the best way to get used to it is to get some CYA standard solution, a solution of CYA with a known quantity of CYA in it, normally its 50ppm. Once you've mixed up a cloudy solution you can reuse the cloudy solution a few times to refine your technique until you get 50ppm each time. Then run the test using a pool sample.

 

[michacunique]

Thanks for all the responses:

- Yes the first result was from two months ago. I, perhaps mistakenly, put a lot of faith in that initial CYA reading from the pool store. I had some test strips (I know I know) that seemed to confirm the high CYA level. Monitoring it didn't seem necessary, and I couldn't really do anything about CYA until the temperatures came down and I could drain it.
- Thank you for mentioning tftestkits.net, I had missed that when browsing the site (and also am spoiled by the convenience of Prime shipping)
- I tested the pool outdoors late in the day, when the sun had retreated behind my neighbor's house but well before sunset. This would seem to approximate a test in sunlight with my back to the sun, but I could always try it again. Unfortunately the kit only comes with about 6 tests worth of reagents so I don't want to go overboard.
- I am a little surprised that neither the manual that comes with the kit, the instructions on the lid, nor even the detailed instructions on the taylor site (https://www.taylortechnologies.com/ChemistryTopicsCM.ASP?ContentID=36) mention anything about having to test outdoors, or in sunlight, or any specifications on how far away the test vial should be. I've found several mentions on their site about the correct lighting when doing color matching tests, but not for a turbidity test like this one.
- I have been using the trichlor tabs and dichlor shock for about 18 months or so, after a fresh drain and fill of the pool after we moved in. I added CYA after the drain but I don't remember how much, just added what I was instructed when I bought the bottle.
- Where could I get a CYA standard solution?

I'm going to try the test again following the instructions from here and sample from a different part of the pool after letting it run for a bit.

 

[AUSpool]

^CYA standard solution - I'm thought tftestkits.net did keep it but I couldn't find it, I did find some at poolvacparts.com (Buy Taylor Cyanuric Acid Standard 16oz #R-7065-E) but I'm sure there are others, I get mine locally. I've used two different CYA viewing tubes and the standard solution gives me a bit of confidence in the test. My technique is a little different for both to get the same result. I've gone back to the view tube that came with the K-2006.

I would stay away from the trichlor tabs and dichlor shock and switch to liquid chlorine or bleach, (http://www.troublefreepool.com/content/142-how-to-chlorinate-your-pool) and dose it as per pool school http://www.troublefreepool.com/calc.html results for your pool and input.