Newbie Trying To Get Everything Right With No-Chlorine System

[neroden]

So I haven't actually purchased a hot tub yet, but I'm going to. I'm already deep into the expensive process of designing and building a suitable extension to house it indoors. (With mechanical ventilation, tiling, floor drain to the sewer, no direct sunlight on the hot tub so no worries about UV, etc. etc.)

I've already done a lot of research on this and other forums but I have some more questions for the experts here.

This is going to be for therapy; both I and my girlfriend have illnesses which make it very valuable. As such, we will be using it daily, quite possibly for more than 20 minutes.

She, however, has had some very bad allergic reactions to chlorinated pools in the past, including one where she stopped being able to breathe. As such she really doesn't want significant chlorine in the water. I know it's possible she was reacting to chloramines, chlorine gas, or whatever, but this is non-negotiable for her due to the scares in the past. (There's no problem with using chlorine to decontaminate as needed if the water will be completely replaced afterwards, obviously. Based on stories of tubs coming "dirty from factory" I think we may decontaminate before the first use.)

We both have college-level chemistry in our backgrounds, we can do whatever testing is necessary, and we're willing to test daily.

So I'm thinking, based on the recommendations for reliable systems, that my first attempt at chemistry will be 2-step bromine with MPS as oxidizer, added after every soak / daily. (If someone has an alternate suggestion for dealing with the combination of high usage and chlorine allergy, let me know, but so far this sounds like the most plausible.)

First question: what test kit(s) should I get? Where should I order them from? (Amazon.com's only distributor of Taylor tests is very badly reviewed.) Are there any obscure gotchas on the testing with this particular combination? Anything that needs to be checked for with MPS accumulation?

Second question: it seems like this is very high usage compared to typical, so I'm suspecting we'll have to drain and refill more than every three months? We're thinking something in the 400 gallon range, though maybe we should go larger. How often should I expect to have to change the water completely? Or, alternatively, how can I tell when I need to change the water (what do I test / watch for buildup of)? Water's cheap here, FWIW, but it does eat up a lot of time to drain and refill. Every two months I can definitely handle, every month would be mildly annoying, more often than monthly would be a problem.

Third question: ozonator worthwhile to cut needed MPS quantities, or just use MPS? This is an indoor installation with heavy usage, which makes me a bit worried about free ozone in the air. The ventilation will be closed when the hot tub is not in use.

Fourth question: is there anything special I should do as *routine* cleaning when doing a water change (as opposed to if we see something requiring decontamination), or is it sufficient to drain, fill with fresh water and reestablish the chemistry as described here: http://www.troublefreepool.com/threads/84-How-do-I-use-Bromine-in-my-spa-%28or-pool%29 ?

Final question: OK to add borates with bromine, just like with chlorine? I can't think of any reason why it wouldn't be. Borax in the bath is actually recommended for our illnesses, so it seems like a good idea...

[PreservedSwine]

Bromine is roughly 80% chlorine, has more of an odor, and is far more acidic. If you're going to bromine to be chlorine free, I'd suggest a different path.

Chlorine comes in many different chemical compounds, when used properly, it has no odor.

But, it sounds as though it doesn't matter, bromine isn't chlorine, it's in the same halogen chemical family, it smells worse and is more corrosive, but it's not chlorine. Indoors, I would NOT recommend it.

You might want to research biguanides. I would normally not recommend them, but it may be what your looking for.

[Dr. Spa]

Bromine tablets contain chlorine, a 2-step bromine system is typ[ically liquid bromide salts, oxidized to bromine with MPS...there's no chlorine.

With regards to her allergy. Are you on city water? If so, there's FAR more chlorine in the steam from a shower than in a hot tub. FYI, 99.999% of respitory issues around hot tub and pools, are when they're located INDOORS.

[chem geek]

1) You can get the Taylor K-2006 at TFTestkits.net.

2) If you have a high bather load, then an ozonator will help make the water last longer. MPS isn't as great an oxidizer as chlorine so will have more trouble keeping the water clear. You could periodically shock with chlorine, but having an ozonator may let you avoid that. As for how long between water changes, this depends on the system you use, but I'd figure that with no ozonator it would be roughly (1/9) x (Spa Size in Gallons) / (# of Person-Hours Per Day) while with an ozonator you might get close to double that.

3) See answer for question #2 above. For high bather load, an ozonator is worth it.

4) Use Ahh-Some both initially after you get your spa and just before you change the water.

5) Borates can be used with any of the systems. It's most easily added from boric acid.

I agree with the previous posts regarding not using bromine since any allergy or reaction to chlorine is likely to be against all halogens. You basically have two choices. One is to use Nature² (silver ions) with MPS. The other is to use Baquacil/biguanide/PHMB. The former is less expensive than the latter. Another option would be to use chlorine for maintaining the spa but to dechlorinate prior to a soak, probably using hydrogen peroxide to do so since it has the least side effects. You'd then add chlorine again right after your soak (when she's out of the spa and most likely you'd be adding it so she doesn't smell any resulting chloramines). This is obviously a riskier approach, but if it's just the two of you soaking then the risk is very low. Bacteria take 15-60 minutes for every doubling of population under ideal conditions and as for person-to-person transmission of disease, you're likely to be doing that to some extent anyway outside of the tub.

So does your girlfriend use a whole-house water filter to remove chlorine and chloramines from the water or a shower filter? If not, then her reaction may not be with chlorine.

[neroden]

Thanks for all the info....

So does your girlfriend use a whole-house water filter to remove chlorine and chloramines from the water or a shower filter? If not, then her reaction may not be with chlorine.

No. If it's not with chlorine, we have to figure out what it is: it's definitely pool-related, and she's had problems with chlorinated city water in *other* cities.

-- She doesn't really do super-hot showers, so steam from a shower doesn't happen, not significantly.

-- Our city water... well... the treatment method is specifically designed to make sure there are NO chloramines in the outgoing water. (There was a newspaper article about this.)

For details on what our city water looks like (ours is Bolton Point, though we do drink the City of Ithaca water without allergy attacks): http://www.boltonpoint.org/waterquality.html

The chlorine residual at point of use is for Bolton Point water is roughly 0.61 mg / l (~= 0.61 ppm) Now, if I could keep my spa water at THAT chlorine level, I'm sure I could convince her :-) But the recommended spa level seems to be a minimum of 1-2 ppm.

I may be able to convince her that she's not allergic to chlorine proper if I get enough data. Odds are, however, that she actually is allergic to the chloramines, which we are simply *never* exposed to anywhere but pools. I'm not sure what other chemicals tend to show up along with the chlorine which might be problems. The case where she stopped breathing definitely "smelled like" an over-chlorinated pool. It had 60+ people in it, however she was the only one who had her throat close up, stopped breathing, and had to be removed from the pool ASAP, indicating an allergy of some sort. At normal pools, her allergic symptom is itching, however, and washing thoroughly with soap and city water will get it off.

What do you think? Chloramine sensitivity?

She is definitely NOT allergic to iodine -- never had any problems with it. So she isn't allergic to all the halogens. Which is one reason I figured we had decent odds of being safe with bromine.

(Unless... thinking out loud here... bromine generates bromamines. Do bromamines have a high cross-reactivity rate with chloramines? Perhaps there's a way we could test for bromine or bromamine reactions in advance?)

2) If you have a high bather load, then an ozonator will help make the water last longer. MPS isn't as great an oxidizer as chlorine so will have more trouble keeping the water clear. You could periodically shock with chlorine, but having an ozonator may let you avoid that. As for how long between water changes, this depends on the system you use, but I'd figure that with no ozonator it would be roughly (1/9) x (Spa Size in Gallons) / (# of Person-Hours Per Day) while with an ozonator you might get close to double that.

Yeeow. That's an interval of only 18-25 days, depending on hot tub size! Seems worth it to try to figure out how to extend it, at least to 31! I guess an ozonator is a must-have.

FYI, 99.999% of respitory issues around hot tub and pools, are when they're located INDOORS.

I know. We don't really have an option. The subzero temperature shock would be a severe deterrent to usage and would exacerbate the arthritis which we're trying to make *better*. It has to be in a room which is kept above freezing. Since I have a clean design slate for the room, I'm planning beefy mechanical ventilation with a fresh-air intake as well as an outflow (any ideas on that are welcome of course), but I have to keep the room temperature up to about 50F or so, and you cannot do that outdoors, not here in upstate NY. (If only we lived in California -- we'd definitely put it outdoors if we weren't in the snowbelt.)

[neroden]

*accidental duplicate*

[neroden]

*accidental duplicate*

[chem geek]

So if you use Cyanuric Acid (CYA aka stabilizer or conditioner) in the water then the active chlorine level will be lower than the 0.61 ppm FC in the drinking water. I suspect the problem is in commercial/public pools that don't use CYA, most especially for indoor pools. Such pools will have an order-of-magnitude higher active chlorine level because the chlorine is not moderated in its strength.

Or it could be as you say exposure to chloramines that are the problem. That would mean you wouldn't want chlorine in the water while you are sweating since that would produce chloramines. Does she ever take hot baths? I would expect they might be a problem since the chlorine would react with ammonia in her sweat and skin to produce monochloramine that might trigger a reaction.

Bromine does combine with ammonia to form bromamines and they can be even stronger oxidizers so can be irritating to some (because of the bromammonium ion that is formed that then creates Br⁺ atoms which is why bromamines show up in the regular DPD test).

So I gave you three options in an earlier post and you're going have to decide which ones to try. If you want to extend the water the most, then using the Dichlor-then-bleach method but dechlorinating using hydrogen peroxide just prior to your soak may be the best bet. By adding chlorine after your soak, you'll then form chloramines but they'll get oxidized by the next day for your next soak. The main downside is that you won't have any disinfectant in the spa during the time you are in it. So there won't be any prevention of person-to-person transmission of disease, but if it's just you and your girlfriend then you can decide if that's OK -- it's similar to taking a bath together. Any bacteria that are shed will get killed off when you add chlorine right after the soak. It's also more work since there's the extra dechlorinating step with it's FC measurement and hydrogen peroxide dosing -- it takes the same volume of 3% hydrogen peroxide to dechlorinate the amount of FC that comes from the same volume of 6% bleach so you can use PoolMath to calculate that dosage. With this method you should get twice as long between water changes compared to the formula I gave for Dichlor-only which would have been (1/9)x(400)/(2*(30/60)) = 44 days with half-hour soaks of two people so with Dichlor-then-bleach you could get 88 days or around 3 months.

The next best would be Nature² with MPS since at least you'll have disinfection during the soak. You'll probably need to use chlorine on occasion to shock every week or so to keep the water clear -- adding the chlorine after one of your soaks so it will be gone by your next soak.

The Baquacil/biguanide/PHMB doesn't do great in heavy bather loads. It uses hydrogen peroxide as the oxidizer. It's also expensive.

[PreservedSwine]

0.6 ppm is fine while you're in the spa. You'll add a bit more when exiting. If that's the threshold to keep her happy, you'll both enjoy it. And it's a far superior way to keep the water clean than biguainides. Just add your maintenance dose of chlorine AFTER each use. And use an ozone generator, in order to keep the need for shocking the water at a minimum. I love the idea of adding silver ions, but as chemgeek suggested, MPS can be more of an irritiant than chlorine. But even if you don't use MPS often, and may not be getting the maximum efficiency out of the silver; it will still be somewhat effective using chlorine as your main sanitizer. You'll need to drain the water a bit more often the keep the CYA from creeping up, but for an indoor spa, probably not a bad idea anyway. Give an occasional shock with MPS when not using it.

Good luck!

[chem geek]

Also keep in mind that with CYA in the water that chlorine's strength is SIGNIFICANTLY moderated. 1-2 ppm FC with 30-40 ppm CYA in the water even at 104ºF is equivalent to only 0.1 to 0.25 ppm FC with no CYA so far less than the 0.6 ppm you are talking about. Nevertheless, if psychologically you can't stomach 1-2 ppm FC you can as PreserveSwine wrote use 0.6 ppm at the start of your soak. I just think it's ridiculous since CYA is in the water binding to most of the FC so that it won't be reacting with your swimsuits or skin nor outgassing. This is why most people can start their soak with 1-2 ppm FC and not find it to be a problem.

HOWEVER, if the issue is with monochloramines and not chlorine, those are formed quickly and the CYA doesn't help in that case since the FC gets released from CYA as it is consumed. So if monochloramines are the issue, then the lower FC level will help. So starting with 0.6 ppm FC would be OK in this case. I was just giving you a greater extreme of starting with zero, but obviously starting with something small is better than nothing at all. Technically, you'll be forming monochloramine soon into your soak as the ammonia in your sweat reacts with chlorine to form monochloramine, but that will max out at whatever FC level you started with, so 0.6 ppm CC as monochloramine if you started with 0.6 ppm FC.

[Dr. Spa]

So, why not have 0 CYA in the water, and dose the chlorine with an eyedropper, at 1/10 the "normal"?

Wouldn't 0 CYA and 0.3 ppm chlorine have the same effect as roughly 30 ppm CYA and 3 ppm chlorine?

[chem geek]

Yes it would have the same effect but would run out more quickly. So for this situation at very low FC for a soak the CYA doesn't buy you anything. For normal situations, it gives you a reserve capacity of chlorine so that you don't run out (get to zero) as quickly. The CYA lets you have a low active chlorine level while having plenty of chlorine in reserve.

So in a normal situation where you want to maintain a chlorine level in between soaks, not having any CYA in the water would make it much more likely for the very low FC level to run out and get to zero which would of course be bad. Generally speaking, when using chlorine CYA is useful to have as a buffer to hold a larger reservoir of chlorine while moderating its strength so that it's not too strong and lasts longer as a result.