Chemically Challenged And Confused

[trucker11]

this question is driven by the fact that I seem to have developed "hot tub rash" (not sure yet-has anyone ever experienced a rash from the heat of the water? I use it at 102-103 degrees and it seems my back has developed more of a heat related reaction) It is hard to believe my rash could be bacteria caused since 1. our tub is only three weeks old and 2. except for initial cloudiness after everyone jumped in with un rinsed bathing suits etc, our tub has been clear, smells good, and all test are within range. 3. No one else in the family has the rash.

If my "hot tub rash" turns out to be just that, its hard to believe that my tub contains any bacteria. In the first week, after superchlorinating with my chlorine products to clear up the cloudiness(I raised the chlorine level to 10), I used the regimen of non chlorine shock after every use. The water cleared up and maintained between 3 and 5 ppm FC without any other chlorine additions for about a week.

When I went in to get more non chlorine shock, the dealer told me I did not have to use it after every use, so I stopped, and went to once a week. At the same time, I re-read my manual and saw that since i had an ozonator, I did not have to keep the FCs between 3 and 5 and could allow them to be between 1 and 3, so I let them go down. Then all hell seemed to break loose. The ph went up, the chlorine went down and disappeared, and I began adding chlorine every day and then I developed the rash. (all filters were rinsed twice weekly)

So, after reading all the threads here and remaining as confused as ever, my questions are--

1. can your test reading strips show good Chlorine readings and yet you still have a problem with the growth of bacteria?

2. How does one test for Combined Chlorine levels?

3. can i really keep my chlorine level at 1 to 3 with an ozonator?

4. And should i use my non chlorine shock after every use?

thanks for taking the time to repeat what I am sure you must have said a hundred times...

[TinyBubbles]

I'm fairly new to the hot tub world too, but I've learned alot on this site and others about water quality. Your ozonator should not effect how much free chlorine you should have to sanitize, if anything, it could mean that you need to add less to maintain your desired level. As far as adding mps(non-chlorine shock) or dichlor(chlorine) after each use, that is a matter of choice. It should be added daily, and I prefer to do it right after we get out of the tub. Kill all the nasties asap. I go for a free chlorine level of 3ppm after dosing. This way, they are much lower by the time we soak the next day. I, also, have an ozonator. I use a nature 2 mineral cartridge. As for shocking weekly, I do this with MPS. Since I have both the ozonator and N2 cartridge, it really isn't that important, because they seem to keep my tub from building up combined chlorines. I do it anyways, because it seems to make the water really sparkle. What is your alkalinity reading? If it's low, that could be the reason for your ph swing. I adjusted my ph on start up and it's remained constant to this point. As far as the chlorine disappearing, how long does this take after you dose? With an ozonator running and high water temps, it would be normal for them to disappear in about 24 hours. Chlorine can either dissapate out of the water or get used up by oxidizing and sanitizing things in the water. What level of free chlorine is in your tub when you soak? If they are high, you could have a sensitivity to the chlorine. As far as the tub being new, most are wet tested at the factory and could have had some old funky water in the lines. If it was a floor model, people could have wet tested in it. But, you mentioned that you got the free chlorine level up to 10ppm. Did you only do this once? You mentioned using your "chlorine products", plural, what did you use? To test for combined chlorine you simply need to buy a test kit that tests for it. Not all do. The cloudiness is something to consider. Bathing suits that haven't been rinsed out would usually cause foaming, maybe extra gunk on the water line. I'm not sure that they should leave the water cloudy. How do you have your filter cycles set up and how long is your ozonator running each day?

[chem geek]

I'm sorry you've got a rash. I'll try an answer your questions below, but we're still trying to sort out why certain people get rashes or bumps and what can be done about it, whether it's bacteria or sensitivity to certain chemicals.

1. can your test reading strips show good Chlorine readings and yet you still have a problem with the growth of bacteria?

Yes, depending on the type of chlorine test you are using and if you are using non-chlorine shock. If the test strips are similar to the OTO chlorine test (showing different intensity of yellow indicating chlorine level), then this tests Total Chlorine only, not Free Chlorine, and unfortunately MPS registers as Combined Chlorine so will show up adding to Total Chlorine. So it is possible that what you were registering was MPS and not chlorine and that the hot tub was not well sanitized. Though regular use of MPS definitely has the chlorine last longer, I would be surprised if it made the chlorine last as long as you described (though, of course, I could be wrong).

You can easily see if the above is true by taking a bucket of filtered water, measuring the chlorine level with the test strip (should be zero -- tap water might measure a small chlorine level), then add a very small amount (1/8 teaspoon) of MPS to the water and mix, then measure with the test strip. If the test strip shows chlorine, then it's really measuring MPS instead.

2. How does one test for Combined Chlorine levels?

The Taylor K-2006 test kit or the TF100 test kit from tftestkits.com will test all of the needed water parameters of Free Chlorine (FC), Combined Chlorine (CC), pH, Total Alkalinity (TA), Calcium Hardness (CH) and Cyanuric Acid (CYA). CH isn't usually measured in a spa or hot tub except possibly after an initial fill or if there is exposed grout with tile touching the water or if the spa is plaster. Though Taylor has a separate K-2041 kit to remove MPS interference in the CC test, you can also get AquaChek MPS test strips instead.

If you were using MPS regularly, you most likely did not have any CC. So if you measure any, then it's MPS that you are measuring.

3. can i really keep my chlorine level at 1 to 3 with an ozonator?

Hard to say. The bigger issue might be using Dichlor exclusively as your source of chlorine as that will build up CYA and that reduces chlorine's effectiveness. What we don't know is at what point does chlorine become ineffective against the bacteria that causes hot tub itch. My overly conservative recommendation is to use Dichlor for 1 week or 2 at most and then switch to unscented bleach. If you add enough to get to 4 ppm FC after you get out, then normally the chlorine level will drop by the next day (if you use the spa every day). Using MPS regularly might reduce such chlorine drop, but I'd be surprised if there still isn't a measurable drop).

4. And should i use my non chlorine shock after every use?

Also hard to say. Some people have a sensitivity to MPS so clearly they should minimize its usage, but MPS is really good at oxidizing organics and does so before chlorine gets a chance to. Some people have had success using MPS weekly, but I'm still trying to sort out if it makes more sense to use a small amount after each use so that there is a small residual the next time you get in (similar to chlorine). That should not only have chlorine last longer, but should eliminate combined chlorine formation while in the tub and reduce monochloramine smell. On the other hand, an ozonator should, in theory, oxidize organics so the need for MPS should be lessened.

As for the rise in pH, depending on the type of MPS you used, that could have been keeping the pH lower as MPS is acidic unless the manufacturer adds something to it to buffer it and make it more pH neutral. Also, Dichlor is actually acidic when accounting for usage. So while I could understand the pH rising if you stopped using both MPS and Dichlor, I find it strange that it went up still using Dichlor. By any chance, did your TA level rise, perhaps due to some carbonate buffer added by the MPS? What specific MPS product did you use? Does it say on the bottle its ingredients and amounts? A higher TA will lead to more carbon dioxide outgassing and that makes the pH rise more quickly from the aeration of the spa jets.

If you know the size of your spa in gallons and the amounts of MPS and Dichlor you were adding, I can do some calculations to see if I can figure something out with regard to the pH. Also, post your other numbers -- pH, TA and CYA.

Richard

[trucker11]

thanks, I will read this tonight and get back to you after I understand everything you have written