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Thread: adding cya to hot tub?

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    adding cya to hot tub?

    I have not used my hot tub for a few seasons. I just finished cleaning and filling it up with 350 gallons of water. I also have a fiberglass pool and I use the sock method to add cya. I plan on using chlorine as my sanitizer. How should I add the cya....just dump it in or like my pool put it in a sock? If I use the sock method,how long do I have to wait to use the hot tub.

    I also purchased a swg for the hot tub....any tips for them? I would appreciate it.

    Thanks
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    Re: adding cya to hot tub?

    You do not want the CYA just sitting in the bottom, so I think the sock method is still advised. You can get in when you have FC in the spa. Do not have to wait for the CYA to be fully dissolved I would not think.

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    Re: adding cya to hot tub?

    And if you did want the CYA to get into the spa faster, you could start out using Dichlor as your chlorine source since that dissolves readily. Up to you.
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    Re: adding cya to hot tub?

    I use the "sock" method. I had to buy some pure CYA since the first time I had already already used chlorine prior to adding dichlor. So as a result, since I have many years of CYA, (had to buy a bucket) I just use the sock and it works great. On my 2nd fill and it dissolves within a few days no trouble. One application.... No need to monitor the Dichlor. Not that it is hard to do.
    Barrier Reef Pacific1-Pacific color 37'9" X 14'1" fiberglass IG ~ 17,500 gallons, FHPM1.0-2 Jandy FloPro pump, Jandy Aquapure 1400 SWG, Waterco Multicyclone 16 pre filter, Jandy CV580 filter, 3 PAL-2000 RU LED lights, 1 skimmer, 2 main drains, 3 returns, 2" rigid pvc suction and return plumbing, BBB method, TF100 Kit

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    Re: adding cya to hot tub?

    Ok.....I have some cya left over from pool season. Now since its fresh fill can I just shock w/bleach and add cya in a sock? I read people use dichlor then bleach. Am I basically doin the same thing w/bleach n cya?
    20,000 gallon viking fiberglass pool w/aqua comfort heat pump, pentair whisperflo pump 1.5hp autopilot dig-220 swg w/RC42 cell (42,000), pg2000 fiber optic lights
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    Re: adding cya to hot tub?

    Yes. Some people use Dichlor and keep track until they get the amount of CYA they want, and then go to bleach. I just shock with bleach put the correct amount of CYA in a sock and put it in my filtering system and it dissolves. Once it dissolves, I don't worry about it again until my next fill. It usually takes about 2 to 3 days to do dissolve. I use 30 ppm but I would go on chem geeks advice.
    Barrier Reef Pacific1-Pacific color 37'9" X 14'1" fiberglass IG ~ 17,500 gallons, FHPM1.0-2 Jandy FloPro pump, Jandy Aquapure 1400 SWG, Waterco Multicyclone 16 pre filter, Jandy CV580 filter, 3 PAL-2000 RU LED lights, 1 skimmer, 2 main drains, 3 returns, 2" rigid pvc suction and return plumbing, BBB method, TF100 Kit

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    Re: adding cya to hot tub?

    I would return the SWCG and switch to little bromine tablets. You don't have to worry about CYA with bromine, it does a better job sanitizing at hot temperatures and since you replace the water several times a year anyway, why have a SWCG? They're only rated to last like 3-5 years.
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    Re: adding cya to hot tub?

    It's not true that bromine does a better job sanitizing at hot temperatures. That's a myth that comes from using chlorine without any CYA in the water since it will outgas too quickly in that case. With CYA in the water, the active chlorine level is lower such that one loses around 25% of the FC over 24 hours when there is no bather load and no ozonator. Besides, with an SWCG, it can easily provide enough chlorine to maintain the level in between soaks.
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    Re: adding cya to hot tub?

    The reason I prefer bromine over chlorine is because chlorine gasses out at 98 degrees where bromine does not. Chlorine is a more effective sanitizer under 75 degrees. Yes, adding CYA will slow down the problem but CYA is prohibited in indoor commercial pools so I usually try and keep all my hottubs consistant, indoor or outdoor.

    In this case however, I agree with you since the tub is outdoors and he's only maintaining one.
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    Re: adding cya to hot tub?

    I am sorry to disagree with you, but it is not true that chlorine gasses out at 98 degrees faster than bromine when CYA is present. The Henry's Law constant for hypobromous acid is as high (slow outgassing) as 6100 while for hypochlorous acid it is 930 which means chlorine outgases around 6-7 times faster at equivalent molarity if there is no CYA in the water. However, with CYA in the water at hot temperatures, the outgassing rate is roughly similar. We're talking about residential spas and pools on this forum so CYA is not banned and quite frankly not having CYA in the water in indoor pools or spas makes the active chlorine level too high leading to faster oxidation of swimsuits, skin and hair and faster creation of disinfection by-products.

    It is also simply not true at all that chlorine is a more effective sanitizer under 75 degrees. Where are you getting your incorrect information? See the following documents:

    Table B-1 in this EPA document
    Tables 3.3,3.4,3.5 in this World Health Organization (WHO) document
    "CT Log Inactivation Values" tables in this Canadian document
    This paper on chlorine inactivation of viruses
    "Effect of Temperature on Disinfection Capability" and Tables 1 and B-1 to B-6 in this U.S. Army document that explicitly says:

    Effect of Temperature on Disinfection Capability
    Temperature, over the range appropriate for drinking water, affects the rate of disinfection reactions according to the Arrhenius equation, with colder water slowing inactivation rates. For chlorine, and all other disinfectants, pathogen inactivation effectiveness increases as water temperature rises (reference 5). Additionally, for a given CT value, a low C and a high T is more effective than the reverse (i.e., a high C and a low T), underscoring the importance of temperature in disinfection efficacy (reference 5). Virus studies showed that the contact time must be increased by two to three times when the temperature is lowered by 10? C to achieve similar inactivation levels (reference 16).
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    Re: adding cya to hot tub?

    Quote Originally Posted by chem geek
    it is not true that chlorine gasses out at 98 degrees faster than bromine when CYA is present.
    I agreed with you. My argument was when CYA was not present. I later specified that when CYA is present, it is relatively the same.

    Chlorine is less stable than bromine at hotter temperatures (No CYA). That is the beauty of chlorine, its unstableness making it a powerful sanitizer. This is why you add the CYA to moderate strength.

    I understand this is a residential spa we are talking about but the reason NSPF suggests bromine for spas, residential or commercial, besides the fact that many state health departments banned chlorine spas all together, is because of the concentration of bacteria in the water. You are going to see a much higher dosage of bacteria in a hot 300 gallon spa in comparison to a 25,000 gallon pool. Bromine is superior in this case because of its ability to use catalysts to regenerate bromine from bromamines, instead of creating chloramines. You would have to dose the spa almost all the time when using chlorine. I say this because I also clean residential pools/spas as well, not just commercial. Since I only visit once a week for residential, I cannot be there daily to add the necessary chlorine. That is why I use bromine.

    I compare residential to commercial often because of all the regulations for commercial pools. I'd like to assume that these regulations are not just BS but there for a purpose. If NSPF suggests bromine over chlorine for all spas, bromine is the chemical I would still choose.

    In the case of this specific pool, use whatever you want since you're outdoors, unregulated and are already using chlorine. Chlorine is a great sanitizer and with CYA, will do exactly the same job. I just wanted to explain my reasoning for bromine.
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    Re: adding cya to hot tub?

    @Matt Ush

    I will let chem geek (or others) chime in about the NSPF recommendations and temperature effects on chlorine stability....

    I wanted to remind you that this forum is primarily focused on pool/tub owners that do their own chemistry. I our case, we can, and do maintain our pools/tubs daily. The chlorine method for hot tubs we recommend on here does include cya. It also requires testing the tub fairly often (daily is recommended at the beginning) and adjusting appropriately.

    See:http://www.troublefreepool.com/how-d...ol-t10095.html
    By the way, we also have a recommended Bromine method here: http://www.troublefreepool.com/how-d...pool-t102.html

    Both have their place and are effective at maintaining hot tubs when monitored/adjusted properly. And both are aimed at owners maintaining their own chemistry.
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    Re: adding cya to hot tub?

    It is again NOT true that chlorine is less stable at higher temperatures or that its being unstable is what makes it more effective (it is effective because it is very reactive with certain chemicals; but that is different than stability when such chemicals are not present). Chlorine does NOT break down in the very dilute concentrations in spa water even at hot 104F temperatures and without CYA. The only thing that happens is that without CYA the chlorine outgasses faster. It also chemically reacts faster if there is something in the water to react with (some of it oxidizes CYA itself, but at a rate of <= 0.4 ppm FC per day at usual FC/CYA levels). Having CYA in the water properly moderates chlorine's strength so that it no longer outgasses so quickly and reacts more slowly, though still fast enough to kill pathogens quickly. The slower reactions mean it oxidizes skin, swimsuits and hair more slowly. You incorrectly claimed that chlorine was a more effective sanitizer under 75F and I listed the correct information that shows that it is in fact the opposite where chlorine kills more quickly at higher temperatures, yet you persist in making these false claims about chlorine's stability.

    I suggest you read Certified Pool Operator (CPO) training -- What is not taught for a small sampling of the incorrect or incomplete information in one of the best courses out there. Hardly any of the standard pools/spa organizations -- NSPF, APSP, IPSSA, EPA, CDC, state regulations -- understand the chlorine/CYA relationship since they all refer to FC and CYA targets (or restrictions) separately. This is ludicrous given the known science since at least 1974.

    There are quite a few Dichlor-then-bleach residential spa owners who maintain their spas using chlorine alone (the initial Dichlor is to build up some CYA, usually around 30-40 ppm) and are able to go 2-3 or more times longer between water changes as a result and have minimal smell, oxidation of swimsuits skin or hair, and minimal disinfection by-products (especially nitrogen trichloride). Their spas are perfectly disinfected. If one maintains the appropriate FC/CYA level, then bacteria are killed quickly in spas just as they are in pools. In a residential spa without an ozonator, the FC drops around 25% over 24 hours so one can easily dose every day or two to maintain the spa. It is true that this does not work for those who only use the spa once a week (and don't dose in between times) or for a service person who only visits such a spa once a week, but one should not make generalized statements that bromine is always better for spas since it is not. Also, for someone using a saltwater chlorine generator, they get continuous automated dosing and only have to dose extra right after getting out of the spa to handle their bather load.

    Chlorine kills bacteria and inactivates viruses quickly as shown in the table in this post that shows chlorine kill times when the FC is around 10% of the CYA level in colder water (77F). The kill times are even faster at hotter temperatures including those in a spa, not only due to the higher temperature, but that the active chlorine level is higher at higher temperatures at the same FC/CYA ratio. Fecal bacteria are killed with 3-log (99.9%) reductions in less than 1 minute and Pseudomonas aeruginosa in 1.5 minutes (again, it's even faster at spa temps -- well under 1 minute).

    Bromine does not create catalysts to regenerate bromine from bromamine. Again, where are you getting this incorrect information? The way it works is that bromamine (NH2Br) is still an effective disinfectant because (as described in this paper) some if it forms bromammonium ion (NH3Br+) that breaks up into (or reacts as) ammonia (NH3) and a highly reactive positively charged bromine ion (Br+) that is even more reactive than hypobromous acid (HOBr). In fact, this is likely to be the reason why bromine spas can be more irritating to some people -- there are far more reports of skin irritation in bromine spas than in chlorine spas properly managed at appropriate FC/CYA ratios. The bromamines may still be good at disinfecting, but they also cause problems for some.

    Bromine is convenient for those who do not use the spa every day since one can use bromine tabs for dosing in between soaks. That is its primary benefit. However, the disinfection by-products from bromine are worse than those from chlorine (brominated THMs cause cancer while chloroform does not at concentrations found in spas). Bromine also costs more (especially when compared to bleach). It also usually requires shocking with chlorine on occasion because bromine doesn't oxidize all the same chemicals as chlorine. It's still a small risk, but unless one really needs the convenience of bromine and can't dose every day or two, then chlorine can be a better choice especially for those who soak every day or two. Both chlorine and bromine have their place in spas.
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