Cyanuric Acid

[Dietitian]

My spa is never used during the daytime and is never exposed to sunlight. Do I still need to add CYA to my spa?

[chem geek]

If you use chlorine, yes you still need CYA since it significantly moderates chlorine's strength. If you were to use chlorine straight, it would be too strong and would degrade hot tub covers too quickly, would outgas more quickly (so get used up faster), would oxidize skin, swimsuits, etc. more quickly, and so on. At the other extreme, you don't want to use too much CYA so we recommend about one week's worth of Dichlor -- more specifically around 33 ppm Free Chlorine (FC) cumulatively added which results in around 30 ppm CYA. Read Nitro's Approach to Water Maintenance.

[Dietitian]

If you use chlorine, yes you still need CYA since it significantly moderates chlorine's strength. If you were to use chlorine straight, it would be too strong and would degrade hot tub covers too quickly, would outgas more quickly (so get used up faster), would oxidize skin, swimsuits, etc. more quickly, and so on. At the other extreme, you don't want to use too much CYA so we recommend about one week's worth of Dichlor -- more specifically around 33 ppm Free Chlorine (FC) cumulatively added which results in around 30 ppm CYA. Read Nitro's Approach to Water Maintenance.

Is it possible to add CYA by itself instead of using the Dichlor?

[chem geek]

You can if you want to. Pure Cyanuric Acid (CYA) is available at pool stores, but it is slow to dissolve and you probably can't get a small quantity of it. You can get Instant Pool Water Conditioner available at Leslie's and other stores. It's twice as expensive, but for the quantities you will use that may not be a big deal. It mixes instantly with water -- it's a slurry of sodium cyanurate so adds CYA to the water and is close to pH neutral (unlike pure CYA which is acidic).

[Dietitian]

You can if you want to. Pure Cyanuric Acid (CYA) is available at pool stores, but it is slow to dissolve and you probably can't get a small quantity of it. You can get Instant Pool Water Conditioner available at Leslie's and other stores. It's twice as expensive, but for the quantities you will use that may not be a big deal. It mixes instantly with water -- it's a slurry of sodium cyanurate so adds CYA to the water and is close to pH neutral (unlike pure CYA which is acidic).

What about the HTH "Stabil/Conditioner?" Is that PH balanced and quick dissolving?

http://www.thegreathardwarestore.com/Produ...&click=2744

[oldparr]

What about the HTH "Stabil/Conditioner?" Is that PH balanced and quick dissolving?

http://www.thegreathardwarestore.com/Produ...&click=2744

And what about this one:

http://www.spadepot.com/shop/Conditioner-S...s-P9308C64.aspx

[chem geek]

Those are both pure Cyanuric Acid and are slow to dissolve and are not pH balanced. As far as I know, there is only ONE liquid CYA and that is the one I linked to earlier. It's patented so I would be surprised to see any brand other than Natural Chemistry.

[Dietitian]

Those are both pure Cyanuric Acid and are slow to dissolve and are not pH balanced. As far as I know, there is only ONE liquid CYA and that is the one I linked to earlier. It's patented so I would be surprised to see any brand other than Natural Chemistry.

Is it safe to enter the tub after dosing with CYA? Does the powder have to dissolve before using the tub?

[NewB@Spa]

I am not sure why, if you are using Dichlor, you would want to add a separate conditioner. It only takes about a week to get your CYA up to between 20 and 30 ppm. About 3 weeks ago I did an empty and re-fill and started using Nitro's method. I will never use any other method. Used a little bit of chems to get rolling and balanced and now only Chlorox at $2 a gallon

[Dietitian]

I am not sure why, if you are using Dichlor, you would want to add a separate conditioner. It only takes about a week to get your CYA up to between 20 and 30 ppm. About 3 weeks ago I did an empty and re-fill and started using Nitro's method. I will never use any other method. Used a little bit of chems to get rolling and balanced and now only Chlorox at $2 a gallon

I don't have any dichlor. I purchased CYA in powder form when I got my tub, and will use that before switching over to Nitro's start up.

I would like to know about the safety of CYA, however.

[timDIDit]

If you use chlorine, yes you still need CYA since it significantly moderates chlorine's strength. If you were to use chlorine straight, it would be too strong and would degrade hot tub covers too quickly, would outgas more quickly (so get used up faster), would oxidize skin, swimsuits, etc. more quickly, and so on. At the other extreme, you don't want to use too much CYA so we recommend about one week's worth of Dichlor -- more specifically around 33 ppm Free Chlorine (FC) cumulatively added which results in around 30 ppm CYA. Read Nitro's Approach to Water Maintenance.

This topic is of great interest to me, as I suffer from "hot tub itch" just as soon as the Cyanuric Acid number goes up. Accordingly, I have been looking for an alternate chlorination method to dichlor, and I believe that Clorox may be just the answer! This may be a silly question, but I have never seen any specific numbers mentioned with regard to how much Clorox needs to be added, and how often. My tub bather load is pretty consistant at 2 people for one hour per day. The tub is a Hot Spring Vanguard with a capacity of 400 gallons. For the last couple of years, I have found that adding one tablespoon of dichlor per day, plus three tablespoons once a week to shock, keeps my water clear and odorless. The only thing that does get out of control is the CYA. Assuming I start with dichlor, let the CYA build up to 30 ppm, THEN switch over to Clorox, what would be the equivalent "dose" of Clorox versus one tablespoon of dichlor in my tub? Thanks! Tim/

[Dietitian]

http://www.poolcalculator.com/

[NewB@Spa]

It is beneficial to test (with a good drop test kit) every couple of days to see where your FC is to determine proper bleach dosing. The calculator is a tremendous tool, but you still need to accurately determine your Chlorine Demand http://www.poolspaforum.com/forum/index.ph...c=18706&hl= only then can you get a real sense for what you need to add after each soak or as a maintenance. Since I have switched to all bleach I no longer "shock" - there is no need to.

[chem geek]

This topic is of great interest to me, as I suffer from "hot tub itch" just as soon as the Cyanuric Acid number goes up.

Tim,

Can you be more specific as to when you begin to suffer hot tub itch? Do you know how much cumulative Free Chlorine (FC) you've added by Dichlor, both regular addition and by shocking, when you begin to suffer hot tub itch? We've never really gotten a good handle on this, though it seems to occur somehwhere in the range of 1-2 months of Dichlor only use which would be around 100-200 ppm CYA at usual Dichlor dosing levels.

Richard

[timDIDit]

It is beneficial to test (with a good drop test kit) every couple of days to see where your FC is to determine proper bleach dosing. The calculator is a tremendous tool, but you still need to accurately determine your Chlorine Demand http://www.poolspaforum.com/forum/index.ph...c=18706&hl= only then can you get a real sense for what you need to add after each soak or as a maintenance. Since I have switched to all bleach I no longer "shock" - there is no need to.

Thanks, NewB! That makes sense, and probably accounts for the fact no one has come forward with a direct equal. I have a full Taylor kit, and had planned to monitor the FC that way, regardless of what info I gained during my research. Interesting that there is no longer a need to shock. Am I to gather that when Clorox depletes, it leaves no chloramines? Tim/

[timDIDit]

This topic is of great interest to me, as I suffer from "hot tub itch" just as soon as the Cyanuric Acid number goes up.

Tim,

Can you be more specific as to when you begin to suffer hot tub itch? Do you know how much cumulative Free Chlorine (FC) you've added by Dichlor, both regular addition and by shocking, when you begin to suffer hot tub itch? We've never really gotten a good handle on this, though it seems to occur somehwhere in the range of 1-2 months of Dichlor only use which would be around 100-200 ppm CYA at usual Dichlor dosing levels.

Richard

I have not conducted an accurate study, but I'm going to guess that right about the time CYA hits 150, the itching starts. That would be between 1-1/2 and 2 months for me, depending on how much dichlor I have added. I have also noticed that the brand of dichlor I use makes a big difference. I have completely stopped using SpaGuard products, as they all seem to be loaded with CYA. Most of the other leading brands seem to have less. Maybe it's just my imagination, but I know that whenever I used SpaGuard, my CYA levels increased much sooner, and to a higher degree. I generally change my water every 3 months, and it is still clear and odorless at that point, just loaded with CYA. In any event, I don't like to go longer than 90 days, as the dissolved solids start to increase, and I like to keep them down as well. Tim/

[chem geek]

Am I to gather that when Clorox depletes, it leaves no chloramines? Tim/

When you use sufficient levels of chlorine, then breakpoint chlorination occurs continuously so while there is a blip of Combined Chlorine (CC) when you add chlorine after a soak, it drops over the next hour or so.

[chem geek]

I have also noticed that the brand of dichlor I use makes a big difference. I have completely stopped using SpaGuard products, as they all seem to be loaded with CYA. Most of the other leading brands seem to have less. Maybe it's just my imagination, but I know that whenever I used SpaGuard, my CYA levels increased much sooner, and to a higher degree. I generally change my water every 3 months, and it is still clear and odorless at that point, just loaded with CYA. In any event, I don't like to go longer than 90 days, as the dissolved solids start to increase, and I like to keep them down as well.

Tim,

CYA is not added separately to chlorine in Dichlor (or Trichlor) -- it is part of the chemical compound itself. So while different products might have different concentrations of Dichlor, the amount of CYA added per FC added will always be the same for any product. Usually, most dichlor products are nearly pure anyway, but perhaps your non-SpaGuard products are "cut" and are not pure Dichlor, but then you would need to use more of them to get to the same FC level. SpaGuard is dichlor dihydrate as are most Dichlor products (there might be some that are anhydrous, but usually not since it's more of a fire hazard).

The Total Dissolved Solids (TDS) are irrelevant for the most part. They are mostly salt, especially if you switch to using Dichlor-then-bleach. You can go longer than 3 months if you wanted to and still be under 2000 ppm salt at 6 months if you use less than 7 ppm FC per day (about a person-hour of soaking).

Richard

[timDIDit]

I have also noticed that the brand of dichlor I use makes a big difference. I have completely stopped using SpaGuard products, as they all seem to be loaded with CYA. Most of the other leading brands seem to have less. Maybe it's just my imagination, but I know that whenever I used SpaGuard, my CYA levels increased much sooner, and to a higher degree. I generally change my water every 3 months, and it is still clear and odorless at that point, just loaded with CYA. In any event, I don't like to go longer than 90 days, as the dissolved solids start to increase, and I like to keep them down as well.

Tim,

CYA is not added separately to chlorine in Dichlor (or Trichlor) -- it is part of the chemical compound itself. So while different products might have different concentrations of Dichlor, the amount of CYA added per FC added will always be the same for any product. Usually, most dichlor products are nearly pure anyway, but perhaps your non-SpaGuard products are "cut" and are not pure Dichlor, but then you would need to use more of them to get to the same FC level. SpaGuard is dichlor dihydrate as are most Dichlor products (there might be some that are anhydrous, but usually not since it's more of a fire hazard).

The Total Dissolved Solids (TDS) are irrelevant for the most part. They are mostly salt, especially if you switch to using Dichlor-then-bleach. You can go longer than 3 months if you wanted to and still be under 2000 ppm salt at 6 months if you use less than 7 ppm FC per day (about a person-hour of soaking).

Richard

This whole discussion has been tremendously helpful! Since I last posted, I pumped out about 70% of the water in my spa, and refilled. I adjusted the chemistry to get it where it belonged, and have since been using Clorox as the sanitizer. Both of us were having "spa itch" problems due to the high CYA levels. Now that CYA is down near 50, all irritation has stopped, and the spa water has a better "feel" as well as a better smell - a win-win sitation! I probably should have pumped a bit more water out (or perhaps just drained and changed) in order to get the CYA level closer to 30, but that can wait for another day.

Tim/

[chem geek]

I'm really glad this is working out for you. I believe you are the only case where the hot tub itch comes and goes in a way that corresponds so closely to the CYA level (more specifically, to the FC/CYA ratio). In this post I tried to correlate hot tub itch/rash/lung against different water conditions, in particular looking for any correlation with CYA level implied by when the itch would start. There was a very mild correlation after 1-2 months of Dichlor-only use, but it's a very weak correlation since the sample size was so small. The most common reason for problems was too low to zero levels of sanitizer.

It's also possible that in your particular situation, you have a chemical sensitivity to CYA itself (or perhaps to some organic that takes longer to get oxidized due to the lower FC/CYA level that is slower in oxidation rates), though that would be the first time I've heard of that. Notice the table in this post that distinguishes between a rash caused by a chemical reaction vs. a rash caused by a bacterial infection.