Too Much Stabilizer? - Hot Tub Water Chemistry - Pool and Spa Forum

Jump to content


(July 17, 2014) POOLSPAFORUM.COM SITE UPGRADE!


Photo

Too Much Stabilizer?


  • Please log in to reply
12 replies to this topic

#1 Tee

Tee

    Junior Member

  • Members
  • PipPip
  • 39 posts
  • Gender:Male

Posted 14 February 2008 - 09:40 AM

I just put a test strip in both my pool and hot tub and I got reading of 150ppm of stabilizer.

What do you use to bring it down, or do I need to?

I wouldn't think you couldn't be too stable?
Tom
Blythewood, SC
20 x 40 Lazy L Inground vinyl liner
Infinity Aurora Spa bought from EBay
<link removed>

#2 watersentinel

watersentinel

    Junior Member

  • Members
  • PipPip
  • 19 posts

Posted 14 February 2008 - 12:06 PM

Stabilizer or cya can effect the contact time needed to kill certain resistant organisms in your spa. As long as you drain and refill your spa every 4 months you will be fine. Draining your spa is the only way to lower your cya and total dissolved solids levels. Just remember that pools and spas are two different animals and they same rules do not apply to both.

#3 Tee

Tee

    Junior Member

  • Members
  • PipPip
  • 39 posts
  • Gender:Male

Posted 14 February 2008 - 12:09 PM

QUOTE(watersentinel @ Feb 14 2008, 03:06 PM) <{POST_SNAPBACK}>
Stabilizer or cya can effect the contact time needed to kill certain resistant organisms in your spa. As long as you drain and refill your spa every 4 months you will be fine. Draining your spa is the only way to lower your cya and total dissolved solids levels. Just remember that pools and spas are two different animals and they same rules do not apply to both.


So is 150 ppm too much for the spa? I don't want to drain it right now, but I will if I have to.

I sure hope I don't have to drain a 35,000 gallon pool.
Tom
Blythewood, SC
20 x 40 Lazy L Inground vinyl liner
Infinity Aurora Spa bought from EBay
<link removed>

#4 chem geek

chem geek

    Wizard of Water

  • Members
  • PipPipPipPipPip
  • 4,800 posts
  • Gender:Male

Posted 14 February 2008 - 01:27 PM

You can always compensate for the lower disinfection from higher stabilizer, Cyanuric Acid (CYA), levels by using a proportionately higher Free Chlorine (FC) level, but at 150 ppm CYA that would take a lot of chlorine. Fortunately, most bacteria are easy to kill. We're not sure about the bacteria that causes hot tub itch -- sources are mixed about that one. The higher CYA could also slow down breakpoint of ammonia/urea from sweat -- do you notice any chlorine smell from the spa? Also realize that by using Dichlor, for every 10 ppm FC it add it also adds 9 ppm to CYA. If you switched to using unscented bleach or lithium hypochlorite, you wouldn't build up the CYA. Nevertheless, after a fresh refill, you do want some CYA in the water, so you should use Dichlor for about a week or two before switching to unscented bleach (e.g. Clorox Regular 6%). Any chemical should be added slowly over a return flow with the pump running.

#5 poolyeti

poolyeti

    Spa Savant

  • Members
  • PipPipPip
  • 76 posts

Posted 14 February 2008 - 01:43 PM

QUOTE(Tee @ Feb 14 2008, 03:09 PM) <{POST_SNAPBACK}>
So is 150 ppm too much for the spa? I don't want to drain it right now, but I will if I have to.

I sure hope I don't have to drain a 35,000 gallon pool.


150 ppm of CYA is too much for any recreational body of water. Like Richard said, for the chlorine to have any effect, you'd have to add a proportionately higher amount of chlorine. You'd have to be using a prohibitively huge amount of chlorine every time. IMHO, you should drain the spa right away and drain as much as you practically can from you pool. Is it inground or above ground?

#6 watersentinel

watersentinel

    Junior Member

  • Members
  • PipPip
  • 19 posts

Posted 14 February 2008 - 01:46 PM

The CDC instructs you to keep a fc residual of 2-5 ppm in your spa which takes into account the fact that there is cya in the water. The CDC gives no limits for CYA in spa water. So there is no need to drain. Most pathogens except a few are killed within a few minutes and your free chlorine residual is hanging around ready to do it's job if needed. If one were to panic and believe that cya was doubling the contact time necessary to kill pathogens, what would that mean? You would need a fc residual for 4 or 5 minutes instead of 2? We all maintain a fc residual in our spas 24 hours a day, so there is no need to panic. Spas have been maintained with stabilized chlorine for decades.

#7 poolyeti

poolyeti

    Spa Savant

  • Members
  • PipPipPip
  • 76 posts

Posted 14 February 2008 - 01:52 PM

QUOTE(watersentinel @ Feb 14 2008, 04:46 PM) <{POST_SNAPBACK}>
The CDC instructs you to keep a fc residual of 2-5 ppm in your spa which takes into account the fact that there is cya in the water. The CDC gives no limits for CYA in spa water. So there is no need to drain. Most pathogens except a few are killed within a few minutes and your free chlorine residual is hanging around ready to do it's job if needed. If one were to panic and believe that cya was doubling the contact time necessary to kill pathogens, what would that mean? You would need a fc residual for 4 or 5 minutes instead of 2? We all maintain a fc residual in our spas 24 hours a day, so there is no need to panic. Spas have been maintained with stabilized chlorine for decades.


Sentinel, the problem is that with such a high concentration of CYA, the fc residual would probably have to be something like 15ppm to do the same job that a 2-5ppm residual would do if the CYA were within normal boundaries. No one is saying that CYA is bad for you. That's why the CDC doesn't have an upper limit set for it. But at that kind of concentration no reasonable amount of chlorine in te water is going to do the job that it should be doing.

#8 chem geek

chem geek

    Wizard of Water

  • Members
  • PipPipPipPipPip
  • 4,800 posts
  • Gender:Male

Posted 14 February 2008 - 03:56 PM

QUOTE(watersentinel @ Feb 14 2008, 01:46 PM) <{POST_SNAPBACK}>
The CDC instructs you to keep a fc residual of 2-5 ppm in your spa which takes into account the fact that there is cya in the water. The CDC gives no limits for CYA in spa water. So there is no need to drain. Most pathogens except a few are killed within a few minutes and your free chlorine residual is hanging around ready to do it's job if needed. If one were to panic and believe that cya was doubling the contact time necessary to kill pathogens, what would that mean? You would need a fc residual for 4 or 5 minutes instead of 2? We all maintain a fc residual in our spas 24 hours a day, so there is no need to panic. Spas have been maintained with stabilized chlorine for decades.

watersentinel,

What you say about most pathogens getting killed quickly even with higher CYA levels is true, though the literature is unclear about the bacteria that causes hot tub itch (the CT values vary widely from different sources). For example, see this link where CYA is recommended not to be used in spas at all for this reason. I think that's overkill and would lead to over-chlorination. That happens in indoor pools as well where CYA is usually not used (my wife's swimsuits degrade over just one winter season of use in the community center indoor pool that is around 2 ppm FC with no CYA whereas in over 5 summer seasons of use in our own outdoor pool with 3.5 ppm FC and 30 ppm CYA there is virtually no degradation noticeable -- same is true for dry/flaky skin and frizzy hair). However, the kill rates track the hypochlorous acid concentration and that varies almost proportionately with the FC/CYA ratio so higher CYA levels need correspondingly higher FC levels to get the same rate of disinfection and oxidation.

The science of chlorine and CYA was fully determined back in 1973 in the following paper that should be required reading for anyone who thinks that CYA doesn't affect disinfection or oxidation capability. Plus there are many scientific studies showing how higher CYA levels significantly reduce kill rates and we've had hundreds of users in pool forums validate that the same thing holds true for keeping away algae with simple FC/CYA ratios (up to around 3000 ppb phosphate level which is pretty high).

J. O'Brien, J. Morris and J. Butler, “Equilibria in Aqueous Solutions of Chlorinated Isocyanurate”, Chapter 14 in A. Rubin, ed., Chemistry of Water Supply, Treatment and Distribution, 1973 Symposium, (published 1974), Ann Arbor Science, Ann Arbor, MI, pp. 333-358.

This thread includes some posts with links to various scientific studies showing kill times for bacteria, protozoan cysts, etc. at varying CYA levels. The Pinellas pool study data that I refer to and discuss in this thread does show that it takes a very small level of chlorine to kill most bacteria in real pools, but there are other disturbing findings in that study that are inconsistent with the study author's summary.

Richard

#9 Tee

Tee

    Junior Member

  • Members
  • PipPip
  • 39 posts
  • Gender:Male

Posted 15 February 2008 - 06:41 AM

I'm confused, I am going to break this into three sections:

1. Hot tub - I think I will drain and refill the tub. It is a little warmer today and it has been about three months since I drained it.

2. Pool - this one worries me. I use the little 3" chlorine tabs in the skimmers (inground pool) and during the swim season I add 2lbs of dichlor shock once a week. During the off season, I really haven't added anything. The chlorine levels didn't really drop since we stopped swimming, so I only put a puck a month in the skimmers and no shock. The question is - do I have to drain a portion of this water off to get the CYA levels down? Would this be an annual thing? How much do I need to drain? It is a 35,000 gallon inground vinyl pool. If we are not swimming, do I need to do it now, or can I wait? The reason I would like to wait is because the cost of water drops in half between April and October. (they cap the limit on sewer costs because of higher use of sprinkler and people filling their pools)

3. Hot tub chemical use - I use a couple of tablespoons of dichlor shock once a week and about a half a cup of unscented bleach every time we get out of the tub (three times a week). Is it normal for the CYA levels to increase to 150 ppm in three months time? 350 gallon hot tub.
Tom
Blythewood, SC
20 x 40 Lazy L Inground vinyl liner
Infinity Aurora Spa bought from EBay
<link removed>

#10 watersentinel

watersentinel

    Junior Member

  • Members
  • PipPip
  • 19 posts

Posted 15 February 2008 - 07:31 AM

QUOTE(poolyeti @ Feb 14 2008, 04:52 PM) <{POST_SNAPBACK}>
QUOTE(watersentinel @ Feb 14 2008, 04:46 PM) <{POST_SNAPBACK}>
The CDC instructs you to keep a fc residual of 2-5 ppm in your spa which takes into account the fact that there is cya in the water. The CDC gives no limits for CYA in spa water. So there is no need to drain. Most pathogens except a few are killed within a few minutes and your free chlorine residual is hanging around ready to do it's job if needed. If one were to panic and believe that cya was doubling the contact time necessary to kill pathogens, what would that mean? You would need a fc residual for 4 or 5 minutes instead of 2? We all maintain a fc residual in our spas 24 hours a day, so there is no need to panic. Spas have been maintained with stabilized chlorine for decades.


Sentinel, the problem is that with such a high concentration of CYA, the fc residual would probably have to be something like 15ppm to do the same job that a 2-5ppm residual would do if the CYA were within normal boundaries. No one is saying that CYA is bad for you. That's why the CDC doesn't have an upper limit set for it. But at that kind of concentration no reasonable amount of chlorine in te water is going to do the job that it should be doing.


I agree yeti. I didn't mean to imply that cya is bad for you. Chlorine will continue to kill up to a cya level of 500. The concern is that people will be lulled into a false security with long lasting residuals at higher cya levels. At 1 ppm chlorine can do it's job in spas. The 2-5 level recommended is taking cya levels into account. It's strange for me to hear so much talk about cya in residential spas. Until this website I have never seen anyone concerned with it. It's a given that people using chlorine in their spas use dichlor which has cya. If people drain and refill their spas they are never going to have a problem. I'm curious if the advocates of bleach in spas have any evidence showing outbreaks of psudomonas in hot tubs using dichlor. My point is that I'd be much more concerned over spas being ran with no residual sanitizer as a result of using bleach. Psuedomonas multiplies rapidly when fc residual falls below .5 or ph is raised above 8. My goal isn't to say that cya does not bind with chlorine. My point is that there are greater evils in a residential spa. I will leave pool chemistry to you pool professionals. Pool and spa water is so different that it would be irresponsible of me to comment on that. If someone wants to keep their fc residual at .5 in a spa then yes high cya levels would be problematic but there is no reason not to keep a fc residual of 2-5 ppm. You won't have a smell and you won't have skin irritation.

#11 poolyeti

poolyeti

    Spa Savant

  • Members
  • PipPipPip
  • 76 posts

Posted 15 February 2008 - 07:43 AM

QUOTE(watersentinel @ Feb 15 2008, 10:31 AM) <{POST_SNAPBACK}>
I agree yeti. I didn't mean to imply that cya is bad for you. Chlorine will continue to kill up to a cya level of 500. The concern is that people will be lulled into a false security with long lasting residuals at higher cya levels. At 1 ppm chlorine can do it's job in spas. The 2-5 level recommended is taking cya levels into account. It's strange for me to hear so much talk about cya in residential spas. Until this website I have never seen anyone concerned with it. It's a given that people using chlorine in their spas use dichlor which has cya. If people drain and refill their spas they are never going to have a problem. I'm curious if the advocates of bleach in spas have any evidence showing outbreaks of psudomonas in hot tubs using dichlor. My point is that I'd be much more concerned over spas being ran with no residual sanitizer as a result of using bleach. Psuedomonas multiplies rapidly when fc residual falls below .5 or ph is raised above 8. My goal isn't to say that cya does not bind with chlorine. My point is that there are greater evils in a residential spa. I will leave pool chemistry to you pool professionals. Pool and spa water is so different that it would be irresponsible of me to comment on that. If someone wants to keep their fc residual at .5 in a spa then yes high cya levels would be problematic but there is no reason not to keep a fc residual of 2-5 ppm. You won't have a smell and you won't have skin irritation.


Glad to see that we actually do agree after all smile.gif

#12 chem geek

chem geek

    Wizard of Water

  • Members
  • PipPipPipPipPip
  • 4,800 posts
  • Gender:Male

Posted 15 February 2008 - 08:22 AM

QUOTE(Tee @ Feb 15 2008, 06:41 AM) <{POST_SNAPBACK}>
I'm confused, I am going to break this into three sections:

1. Hot tub - I think I will drain and refill the tub. It is a little warmer today and it has been about three months since I drained it.

2. Pool - this one worries me. I use the little 3" chlorine tabs in the skimmers (inground pool) and during the swim season I add 2lbs of dichlor shock once a week. During the off season, I really haven't added anything. The chlorine levels didn't really drop since we stopped swimming, so I only put a puck a month in the skimmers and no shock. The question is - do I have to drain a portion of this water off to get the CYA levels down? Would this be an annual thing? How much do I need to drain? It is a 35,000 gallon inground vinyl pool. If we are not swimming, do I need to do it now, or can I wait? The reason I would like to wait is because the cost of water drops in half between April and October. (they cap the limit on sewer costs because of higher use of sprinkler and people filling their pools)

3. Hot tub chemical use - I use a couple of tablespoons of dichlor shock once a week and about a half a cup of unscented bleach every time we get out of the tub (three times a week). Is it normal for the CYA levels to increase to 150 ppm in three months time? 350 gallon hot tub.

A couple of tablespoons of Dichlor in 350 gallons increases the Free Chlorine (FC) by 11.8 ppm and increases the Cyanuric Acid (CYA) by 10.8 ppm. So after 3 months (12 weeks) the Dichlor would add 10.8*12 = 130 ppm CYA which is about what you are seeing.

The 3" chlorine tabs in the pool are probably Trichlor pucks and if they are 8-ounce pucks, then each one in 35,000 gallons adds 1.6 ppm to Free Chlorine (FC) and 1.0 ppm to Cyanuric Acid (CYA). The two pounds of Dichlor in 35,000 gallons adds 3.8 ppm FC and 3.5 ppm CYA. I don't know how many pucks you use per week, but you can see that the CYA level can build up for the pool as well when you used stabilized sources of chlorine.

If you are going to have the CYA level high, then to ensure that you don't get algae (in the pool) I suggest you use a weekly PolyQuat 60 algaecide (or a phosphate remover, but that can get expensive). If you want to avoid increasing the CYA level, then you would need to use unstabilized chlorine such as chlorinating liquid (or Cal-Hypo, but for every 10 ppm FC added by Cal-Hypo it also increases Calcium Hardness by 6 ppm). And yes, only a partial drain/refill will reduce the CYA level.

Richard

#13 chem geek

chem geek

    Wizard of Water

  • Members
  • PipPipPipPipPip
  • 4,800 posts
  • Gender:Male

Posted 15 February 2008 - 08:39 AM

QUOTE(watersentinel @ Feb 15 2008, 07:31 AM) <{POST_SNAPBACK}>
I agree yeti. I didn't mean to imply that cya is bad for you. Chlorine will continue to kill up to a cya level of 500. The concern is that people will be lulled into a false security with long lasting residuals at higher cya levels. At 1 ppm chlorine can do it's job in spas. The 2-5 level recommended is taking cya levels into account. It's strange for me to hear so much talk about cya in residential spas. Until this website I have never seen anyone concerned with it. It's a given that people using chlorine in their spas use dichlor which has cya. If people drain and refill their spas they are never going to have a problem. I'm curious if the advocates of bleach in spas have any evidence showing outbreaks of psudomonas in hot tubs using dichlor. My point is that I'd be much more concerned over spas being ran with no residual sanitizer as a result of using bleach. Psuedomonas multiplies rapidly when fc residual falls below .5 or ph is raised above 8. My goal isn't to say that cya does not bind with chlorine. My point is that there are greater evils in a residential spa. I will leave pool chemistry to you pool professionals. Pool and spa water is so different that it would be irresponsible of me to comment on that. If someone wants to keep their fc residual at .5 in a spa then yes high cya levels would be problematic but there is no reason not to keep a fc residual of 2-5 ppm. You won't have a smell and you won't have skin irritation.

There were 7 reported cases of hot tub itch on this forum -- 4 initially quite a while ago with one case diagnosed by a doctor as hot tub itch and the other hot tub lung. All of these occurred after 1.5 months or more of Dichlor-only use except for one case where only MPS was used and there was zero chlorine residual. That doesn't prove anything, but it's what got me looking at the issue in spas.

The main difference in a spa is the vastly higher bather load compared to a pool (in a residential setting in particular). How do you maintain an FC residual of 2-5 ppm when one person-hour of soaking seems to consume around 7 ppm FC in 350 gallons? This is the biggest problem people have had regardless of using Dichlor or bleach. If one uses MPS to supplement, then that helps, but the amount of ammonia/urea from sweat that needs to get broken down is still rather large. Also, long before anyone mentioned bleach on this forum, virtually all spa users were adding Dichlor AFTER they soaked (i.e. the Vermont/Northman method) and most tried to soak with minimal chlorine and this was not due to any scare tactics about having minimal chlorine exposure but had to do with avoiding the smell of chlorine combining with ammmonia/urea from sweat (i.e. forming monochloramine). If one uses a residual of MPS during their soak, then this will prevent smelly monochloramine formation, but several people had skin sensitivities to MPS so that was not an option for them.

So how do you keep the FC residual at 2-5 ppm during a 2-person half hour soak? And how do you avoid the smell of monochloramine other than through use of MPS or having a very low FC during the soak? The recent report of soaking at 9 ppm FC with 40 ppm CYA with one person had no smell so the monochloramine may be getting broken down about as fast as ammonia/urea is getting added from sweat, but that would require higher disinfecting chlorine (hypochlorous acid) levels if you have more people soaking and that seems impractical.

Richard




0 user(s) are reading this topic

0 members, 0 guests, 0 anonymous users

website security