CYA levels… how did that happen?

[Andrew Montreal]

Hi all,

I had brought my CYA levels to around 30-35 ppm… hard to be precise with that test. I then switched to liquid chlorine. It’s been almost two weeks.

This morning I realized I hadn’t put chlorine in the tub in a day and a half. I went to check and it was at 1 ppm so I brought it up to 5 ppm with liquid chlorine.

I decided to also check my other chemicals and saw that the pH was then above 8.0. Okay… something happened. The TA was at 75… after the seventh drop it was so close to having changed colour that I figured it was somewhere between 70 and 80.

But the real weird issue is the CYA levels… they were reading 50 ppm. How can that be? I haven’t added dichlor since reaching at most 35ppm (a value equally confirmed by my calculations.)

One ridiculous error… I actually can’t recall if I measured the CYA before or after having added the pH-

Does pH play with CYA readings? Does the dry acid affect the CYA readings?

Thanks,

Andrew

 

[Bperry]

Hi all,

I had brought my CYA levels to around 30-35 ppm… hard to be precise with that test. I then switched to liquid chlorine. It’s been almost two weeks.

This morning I realized I hadn’t put chlorine in the tub in a day and a half. I went to check and it was at 1 ppm so I brought it up to 5 ppm with liquid chlorine.

I decided to also check my other chemicals and saw that the pH was then above 8.0. Okay… something happened. The TA was at 75… after the seventh drop it was so close to having changed colour that I figured it was somewhere between 70 and 80.

But the real weird issue is the CYA levels… they were reading 50 ppm. How can that be? I haven’t added dichlor since reaching at most 35ppm (a value equally confirmed by my calculations.)

One ridiculous error… I actually can’t recall if I measured the CYA before or after having added the pH-

Does pH play with CYA readings? Does the dry acid affect the CYA readings?

Thanks,

Andrew

CYA can take time to register on the test. How long did you wait after dissolving it before testing initially?

 

[Andrew Montreal]

CYA can take time to register on the test. How long did you wait after dissolving it before testing initially?

Not sure I understand…with the test I have there is no dissolving. I am mixing a liquid with the test water.

But I waited the required 30 seconds before putting the mixture into the test vial to see when the black dot disappears. But I also checked the test again one minute later.

 

[Gebo]

Cyanuric Acid (CYA)

tftestkits.net

This is what I use to check CYA. It is very accurate and goes down to 20.

 

[Bperry]

Not sure I understand…with the test I have there is no dissolving. I am mixing a liquid with the test water.

But I waited the required 30 seconds before putting the mixture into the test vial to see when the black dot disappears. But I also checked the test again one minute later.

No, when you added stabilizer to the spa? water. If you used dichlor then I don’t know if that have the same timeframe to react to testing that pure CYA does.

I mean that after CYA is added to the water, it takes time for the level to show up on a test. If you tested too soon after adding, it may have continued to rise after you tested.

 

[duraleigh]

This won't solve your issue but may help you refine your testing

1. pH does not alter CYA readings......they are unrelated

2. Accuracy of CYA test is +/- is10-15 ppm

3. TA is measured in 10 ppm increments (60,70,80)

4. The end point on all drops based test is when the last drop produces no FURTHER color change......then subtract that last drop

Sorry I can't answer your real question about CYA........it is usually operator error unless, like bperry suggests, you tested right after putting it in.

 

[Andrew Montreal]

No, when you added stabilizer to the spa? water. If you used dichlor then I don’t know if that have the same timeframe to react to testing that pure CYA does.

I mean that after CYA is added to the water, it takes time for the level to show up on a test. If you tested too soon after adding, it may have continued to rise after you tested.

Ahh… I apologize if I wasn’t clear enough. As I mentioned in my first post, it has been almost two weeks that I am no longer using dichlor. I have been using liquid chlorine since, thus no more CYA is being added.

 

[Andrew Montreal]

This won't solve your issue but may help you refine your testing

1. pH does not alter CYA readings......they are unrelated

2. Accuracy of CYA test is +/- is10-15 ppm

3. TA is measured in 10 ppm increments (60,70,80)

4. The end point on all drops based test is when the last drop produces no FURTHER color change......then subtract that last drop

Sorry I can't answer your real question about CYA........it is usually operator error unless, like bperry suggests, you tested right after putting it in.

Thanks for the input. The idea of the last drop then subtract one is new to me. I had perhaps missed that in the instructions. Good to know.

I was being playful with the 75ppm because I felt that the test really suggested that it was between the two. But based on what you’ve said, I have a reading of 80ppm.

As for the CYA… I haven’t added any in almost two weeks.

What else could affect CYA readings?

 

[Andrew Montreal]

Cyanuric Acid (CYA)

tftestkits.net

This is what I use to check CYA. It is very accurate and goes down to 20.

Is it more accurate than the Taylor test?

 

[JoeSelf]

We're both tests done in full sunlight w sun at back? Test tube at waist. Pour to each line and look for the dot. CYA is 10s only.

That's why I use dichlor to get my CYA. I add it slowly during the first week or so until I get to 30. I use effects of adding for numbers.

 

[Bperry]

Ahh… I apologize if I wasn’t clear enough. As I mentioned in my first post, it has been almost two weeks that I am no longer using dichlor. I have been using liquid chlorine since, thus no more CYA is being added.

So when did you measure 35ppm CYA and when did you measure 50ppm? The CYA test sample is recommended to be at room temperature or above but not sure if there’s a “too hot” temperature that also applies, assuming this is a heated tub.

Best advice is to just keep track of it and chlorinate accordingly. The test tolerance is pretty close to your results so maybe just par for the course.

 

[JoeSelf]

It's the same stuff as the Taylor test kit.

 

[Gebo]

Is it more accurate than the Taylor test?

Yes. It goes down to 20 and Taylor stops at 30. Well, I better be careful. The Taylor test kit I have only goes to 30.

 

[Andrew Montreal]

We're both tests done in full sunlight w sun at back? Test tube at waist. Pour to each line and look for the dot. CYA is 10s only.

That's why I use dichlor to get my CYA. I add it slowly during the first week or so until I get to 30. I use effects of adding for numbers.

There is no sun today. It’s overcast. But I did it outside.

Same here… I used dichlor for a couple of weeks till I got it to around 30-35ppm. My Taylor tests showed that. I also used the Effects Of Chemicals to confirm the amount of CYA I had added. Over that period I had added 110g of dichlor which n my hot tub results in 33ppm of CYA. That’s why today’s test surprised me.

 

[duraleigh]

Is it more accurate than the Taylor test?

No, but it requires a larger pool water sample that takes a reasonable reading at 20.

Either test is fine. I like the extra range but it is seldom, if ever, used for TFP methodology.

The CYA test is frustrating to many because we all want more precision. That precision is unavailable for CYA but luckily, it is not needed.

 

[Andrew Montreal]

So when did you measure 35ppm CYA and when did you measure 50ppm? The CYA test sample is recommended to be at room temperature or above but not sure if there’s a “too hot” temperature that also applies, assuming this is a heated tub.

Best advice is to just keep track of it and chlorinate accordingly. The test tolerance is pretty close to your results so maybe just par for the course.

I measure around 35ppm when I stopped using dichlor and which was around eleven days ago. I measured 50ppm today.

It’s a heated tub and I always cool the water down first before testing. I had read in the Taylor documentation that the water can’t be above a certain temperature… don’t recall the exact number but I cool mine down to just above tepid.

As for tracking, I used dichlor for a couple of weeks till I got it to around 30-35ppm. My Taylor tests showed that. I also used the Effects Of Chemicals to confirm the amount of CYA I had added. Over that period I had added 110g of dichlor which in my hot tub results in 33ppm of CYA. That’s why today’s test surprised me.

I imagine it could be a margin of error affair or perhaps someone has been snooping around throwing stuff in my hot tub. I kid... There’s no one here.

 

[Andrew Montreal]

No, but it requires a larger pool water sample that takes a reasonable reading at 20.

Either test is fine. I like the extra range but it is seldom, if ever, used for TFP methodology.

The CYA test is frustrating to many because we all want more precision. That precision is unavailable for CYA but luckily, it is not needed.

I hear what you’re saying. The calculated numbers show that I am fine. I will do another CYA test in a week or so. In the meantime, the rest of my chemicals are okay.

 

[kul]

After adding CYA to my pool I usually wait at least 3-4 days or even a week to test because it takes a while for it to really get dissolved and distributed. At least that’s what I tell myself. It usually works out ok.

Since a spa is smaller and all jetty (or whatever it’s called), maybe the rules are different?

 

[Andrew Montreal]

A second question though… I can assume that my hot tub was at 1ppm overnight. Is that a big issue? It’s now been brought back up to 5ppm. I should also mention that it does also happen that overnight my UV/ozone cleaner (Jacuzzi’s Clearray) is also running.

 

[Andrew Montreal]

After adding CYA to my pool I usually wait at least 3-4 days or even a week to test because it takes a while for it to really get dissolved and distributed. At least that’s what I tell myself. It usually works out ok.

Since a spa is smaller and all jetty (or whatever it’s called), maybe the rules are different?

Also, I haven’t added CYA in 11 days.