Hot Tub Cough

[Accent]

Hi,

About one month into my first refill on my hot tub, I've started coughing when inside it or even when just checking the water or adding chemicals. I am more sensitive when the jets are on, but I still feel sensitive sometimes without them. I've read about hot tub lung, which sounds scary, but I don't have any of the fatigue-type symptoms - at least not yet!

My current set-up is dichlor with Nature 2 and an ozonator on a 260 gallon tub. I had no coughing problems during my first 3-month fill, when I did not use Nature 2, but used dichlor and the ozonator. I've also been using a scum bug, which sometimes seems to block the filter a bit, but I already tried removing it with not much difference. The only triggers I can think of are that the coughing/breathing trouble started after I rinsed my filter and used a small amount of clarifier, and I switched the filtration from 6 hour cycles to 4. I used an over the counter test to check for bacteria today (psduedomonas) and it came out negative. I don't have any itch problems, just the respiratory ones. I've tried shocking, but that hasn't helped much so far. The water balance seems ok. My CYA level is not too high right now.

I've seen somewhat similar posts from long ago here - anyone have any success in fixing it? Should I re-drain? Get rid of Nature 2?

Thanks.

[Whoneedsavacation]

Are you sure your chlroine levels aren't too high? Too much chlorine gas (or bromine for that matter) could cause irritation. Or maybe you are allergic to something that happens to be blooming next to the tub?

[Accent]

Are you sure your chlroine levels aren't too high? Too much chlorine gas (or bromine for that matter) could cause irritation. Or maybe you are allergic to something that happens to be blooming next to the tub?

I think it's unlikely they're too high. My routine is to use a tsp of dichlor after night use (usually 1 person for 15 minutes), and when I test it in the morning, it's almost always under 1 ppm. I know that's less than most people in this group recommend, but it's the method recommended to me by my dealer and I figured with the ozonator it would be enough; plus I had no health problems with this system for the first fill, though occasionally the water would be cloudy.

I'm not allergic to any plants in my yard, but would lemon blossoms getting in the tub make a difference? T'is the season.

[Accent]

Hi,

About one month into my first refill on my hot tub, I've started coughing when inside it or even when just checking the water or adding chemicals. I am more sensitive when the jets are on, but I still feel sensitive sometimes without them. I've read about hot tub lung, which sounds scary, but I don't have any of the fatigue-type symptoms - at least not yet!

My current set-up is dichlor with Nature 2 and an ozonator on a 260 gallon tub. I had no coughing problems during my first 3-month fill, when I did not use Nature 2, but used dichlor and the ozonator. I've also been using a scum bug, which sometimes seems to block the filter a bit, but I already tried removing it with not much difference. The only triggers I can think of are that the coughing/breathing trouble started after I rinsed my filter and used a small amount of clarifier, and I switched the filtration from 6 hour cycles to 4. I used an over the counter test to check for bacteria today (psduedomonas) and it came out negative. I don't have any itch problems, just the respiratory ones. I've tried shocking, but that hasn't helped much so far. The water balance seems ok. My CYA level is not too high right now.

I've seen somewhat similar posts from long ago here - anyone have any success in fixing it? Should I re-drain? Get rid of Nature 2?

Thanks.

OK, so I did a bunch of research online and learned about something I haven't seen here before: biofilms. They're the stuff that helps bacteria stick to the hot tub (and protect them from disinfectants), but they get loosened up and aerosolized by the jets and make people cough and get sick when they breath them. See Montana State article.

It's a relatively new field of research and it's not clear what all works to break them down (mixed reviews on enzymes), but ozone is supposed to be effective (see here) and it seems to me that my switching my filtration/ozone cycles to 4 hours from 6 may have been the trigger to this problem after all. I also hadn't used enzymes on this fill because the Nature 2 had made the water seem so clear I didn't think I needed them. But maybe they had helped prevent biofilm build up in the first fill.

Anyway, I have drained my spa and will let it dry out a couple days and will start all over with more ozone and more filter-cleaning and see if that helps. I'll let you all know if it works. In the meantime, maybe we all need to become biology geeks!

[chem geek]

Bacteria don't start out with biofilms. Bacteria get introduced into the water, oftentimes from your skin, and then if the disinfectant level is low they multiply, find a surface of the hot tub, and then secrete substances to form a biofilm. So if the bacteria are killed early before they take hold on surfaces and generate enough of a biofilm to resist getting disinfected, then this can prevent the problem early on.

The ozonator is unlikely to do anything to prevent biofilms because the ozone does not persist long enough in the bulk pool water -- instead, the ozone mostly oxidizes organics that pass through the ozonator and also kill free-floating bacteria that pass through it, but it takes 4.6 turnovers to have 99% of the water cycle through and that takes hours. Bacteria double in population in 15 minutes to an hour under ideal conditions (perhaps even faster at hot tub temps).

I am a bit surprised that the use of Nature2 didn't help since it does generally prevent runaway bacterial growth, but it is slow-killing by itself so maybe not fast enough to prevent a biofilm from forming. The several hot tub itch and one hot tub lung incidents I've been tracking here may indicate that somewhere between 1-2 months of Dichlor use may increase CYA levels to the point where the chlorine isn't fast-killing enough against bacteria to prevent hot tub itch or hot tub lung. However, your experience would the first where this would have occurred when using Nature2.

Many spa users don't use enough chlorine so it ends up getting to zero for long enough periods of time before the next soak or during the soak that bacteria can grow, possibly fast enough to form hearty biofilms on surfaces. Do you know how often you soaked (how many times per day and days per week), for how long (30 minutes?), how many people, and how much chlorine you used in how many gallons? That info might help me figure out if enough chlorine was used. The rough rule I've been using is 7 ppm FC in 350 gallons per person-hour of soaking.

Richard

[Accent]

Many spa users don't use enough chlorine so it ends up getting to zero for long enough periods of time before the next soak or during the soak that bacteria can grow, possibly fast enough to form hearty biofilms on surfaces. Do you know how often you soaked (how many times per day and days per week), for how long (30 minutes?), how many people, and how much chlorine you used in how many gallons? That info might help me figure out if enough chlorine was used. The rough rule I've been using is 7 ppm FC in 350 gallons per person-hour of soaking.

Richard

Usually one person for about 15 minutes almost every night. The tub had gone over a week with no chlorine on the prior fill (pre-nature 2), and since it sounds like biofilm colonies can live in the pipes, it's possible that maybe they were allowed to grow then and just stuck around. Does your equation mean maintaining continuous 7ppm?

How many circulation hours do you think it would take for the ozone to get 99% of the water? It may support my theory that keeping the ozone/filtration cycles longer would help. And my chlorine levels have been higher since the coughing started, but it did not help the problem. This makes me think it was too little too late in combatting the biofilm.

By the way, this situation seems pretty serious to me. It got to the point where I couldn't be near the tub with the jets on and I felt the effects for hours after. I'm an athlete and have strong lungs (for now), so this concerns me a lot. But I love my tub!

[chem geek]

Assuming your tub is 350 gallons, the one person for 15 minutes would create a rough chlorine demand of 1.8 ppm FC which would require one teaspoon of Dichlor to be added for each soak (usually added right after you soak). However, to really know how much chlorine you should use, you add chlorine after your soak and then measure just before your next soak the next day -- you should measure at least some small amount of residual chlorine. If you do not, then you need to use more chlorine. The more typical soak time is 30 minutes and 2 teaspoons of Dichlor added after the soak.

It takes 4.6 turnovers of the water to circulate 99% of the water. How long that takes depends on how long it takes for your spa pump to circulate the water. With the jets off, I'm guessing that the circulation pump may not be very fast, say 20 GPM or so. Others may know what the more typical number is. If I assume 20 GPM, then that.s 17.5 minutes for a turnover so about 80 minutes for 99% of the water to circulate. However, this does nothing for bacteria that sticks itself to surfaces -- no number of turnovers will help there. This is why the residual chlorine level (or, in theory, the metal ions of Nature2) are your only disinfectant that can kill such bacteria stuck to surfaces before they multiply and excrete to the point where a strong biofilm is formed. Basically, you should not consider the ozone to be disinfecting your water for bacteria -- it is primarily an oxidizer. For pathogens that don't multiply outside a host (and don't usually stick to surfaces and form biofilms), such as viruses and protozoan oocysts, those can be killed by the ozonator over time.

You can drain and superchlorinate your hot tub to get rid of any biofilms. See this post by Hillbilly Hot Tub.

Richard

[Accent]

Assuming your tub is 350 gallons, the one person for 15 minutes would create a rough chlorine demand of 1.8 ppm FC which would require one teaspoon of Dichlor to be added for each soak (usually added right after you soak).

It takes 4.6 turnovers of the water to circulate 99% of the water. How long that takes depends on how long it takes for your spa pump to circulate the water. With the jets off, I'm guessing that the circulation pump may not be very fast, say 20 GPM or so. Others may know what the more typical number is. If I assume 20 GPM, then that.s 17.5 minutes for a turnover so about 80 minutes for 99% of the water to circulate. However, this does nothing for bacteria that sticks itself to surfaces -- no number of turnovers will help there. This is why the residual chlorine level (or, in theory, the metal ions of Nature2) are your only disinfectant that can kill such bacteria stuck to surfaces before they multiply and excrete to the point where a strong biofilm is formed. Basically, you should not consider the ozone to be disinfecting your water for bacteria -- it is primarily an oxidizer. For pathogens that don't multiply outside a host (and don't usually stick to surfaces and form biofilms), such as viruses and protozoan oocysts, those can be killed by the ozonator over time.

You can drain and superchlorinate your hot tub to get rid of any biofilms. See this post by Hillbilly Hot Tub.

Richard

Thanks, Richard. My tub is 260 gallons.

The reason I asked about the amount of time it took for water to interact with the ozone is because of the article I linked to in my original post indicated that ozone is effective in cutting up the biofilm to allow the chlorine to get to the bacteria. I did superchlorinate my tub before draining, but I'm concerned that wouldn't be effective without the ozone enabling access to the bacteria that have been protected by the biofilm.

Here is the link again (not a fabulous article, but a start): http://www.prozoneint.com/pdf/biofilms.pdf. It notes that gaseous ozone is best, and suggests cutting off the circulation route to water in order to use gaseous ozone, but I can't figure out if that is possible - are they suggesting developing a new kind of spa to allow that? Or does a typical ozonator produce gaseous ozone that maintains its state within the water?

On another note, having read the discussions that using mps + Nature 2 with occasional dichlor is effective, I was considering alternating between 1 tsp of dichlor and 1 tbs of MPS post-soak. That is, use dichlor one day and MPS the next. I still like the idea of cutting back on chlorine, particulary given the CYA issue, and think more MPS would help, though I don't want to use it daily. I have tried bleach on occasion and think that after awhile I'd be frustrated by the ph issues. What do you think?

[Hillbilly Hot Tub]

On another note, having read the discussions that using mps + Nature 2 with occasional dichlor is effective, I was considering alternating between 1 tsp of dichlor and 1 tbs of MPS post-soak. That is, use dichlor one day and MPS the next. I still like the idea of cutting back on chlorine, particulary given the CYA issue, and think more MPS would help, though I don't want to use it daily. I have tried bleach on occasion and think that after awhile I'd be frustrated by the ph issues. What do you think?

Since your spa does not fall under heavy use, you could try the low chlorine recipe included in the N2 package. If it does not work well, you can go back to adding chlorine all the time such as you have been doing without draining the tub. If you do this low chlorine recipe, you must filter/ozone a minimum of 4 hours 2 times per day. Just read the recipe and follow it exactly. Also, get a high quality MPS (they range from 30-45% active ingreident usually) with the higher active ingreidient. The lower ones seem to have some kind of inhert ingreidient that causes a white reidue on the spa edge and swimsuits. We have had no issue with the higher quality ones and no problem with the TDS getting to high even when added daily.

[cplarsen]

Umm, since he's worried about biofilms, I wouldn't recommend a low chlorine routine at all.

Go high, and just dump and refill more often to cover the CYA problem.

btw, I notice a slight cough problem from my tub too. But it hasn't returned since I quit worrying about nailing the numbers exactly. These days, I just throw in a tablespoon of dichlor a day, period, and shock once a week with MPS.

Sure it's more than needed, but chlorine and water are cheap.

[Hillbilly Hot Tub]

Umm, since he's worried about biofilms, I wouldn't recommend a low chlorine routine at all.

Go high, and just dump and refill more often to cover the CYA problem.

btw, I notice a slight cough problem from my tub too. But it hasn't returned since I quit worrying about nailing the numbers exactly. These days, I just throw in a tablespoon of dichlor a day, period, and shock once a week with MPS.

Sure it's more than needed, but chlorine and water are cheap.

MPS is an oxidizer, thus doing the same thing as ozone if not better. It will work on breaking down the stuff causing biofilms and allow the N2 and chlorine to become more effective in sanitizing since it is not working so hard oxidizing.

[chem geek]

I agree with Hillbilly Hot Tub. From my discussions last year with Dupont who make most MPS sold in the U.S., uncatalyzed MPS is a strong, but kinetically-selective oxidizer. It is not expected to oxidize all organic matter. Anecdotally, it seems to have some efficacy at breaking down or inhibiting biofilms. Dupont does not have hard data on that and don't make marketing claims about it.

For the biofilms to form in the first place, I suspect the chlorine level may have been too low, but the only way to know that would have been to test the chlorine level prior to soaking. Of course, not having any significant chlorine level during soaking, which is what most users do, could let bacteria start to form biofilms during the soak. Hopefully in most cases the addition of chlorine immediately after the soak is enough to take care of the relatively immature biofilm.

Richard

[cplarsen]

Which was my point.

Avoid the low chlorine level in the first place, then the rest becomes academic.