Strong 'skin sensitivity' reaction to Bromine hot tub. How to do a bathtub test for a “Chlorine” reaction?

[Davekro]

[Edit: My wife told me her Dr. said she had a skin ‘sensitivity’ to Bromine, not an ‘allergic reaction’. I have changed my references to ‘allergy/allergic’ to ‘skin sensitivity’. The link says that ‘skin sensitivity’ (irritant contact dermatitis) shows a reaction, rash, in 1–2 hours (which she had), whereas ‘allergic contact dermatitis’ is an immune system reaction that takes from 24 to 48 hours to show symptoms. The ‘skin sensitivity reaction’ was quite severe for her, so it is still a significant issue. This article talks about testing patches of skin on your arm, like a dermatologist would do. I’ll have her ask her Dr. if he/she can recommend a chlorine % solution to apply to her arm as a chlorine sensitivity test, rather than dunking her whole body in a bathtub of chlorinated water!]

Before we go through the hassle of draining the tub and restarting with Chlorine as the sanitizer instead of Bromine, to see if Chlorine causes my wife no skin rashes, we want to fill the bathtub with hot water and simulate the chlorine water conditions that would be the same as if we convert the hot tub to chlorine.

So here are our questions:
1) Is it common for some people to have a skin sensitivity reaction to Bromine, but NOT to Chlorine? What are the odds of this? (I’ll have her ask her Dr. about this too.)

2)How do I create a bathtub chlorine environment to match a hot tub's? [We may hold off for a possible arm skin patch test for chlorine if that is an option.]

a) Would I need to reduce our tap water's 370 ppm TA (Total Alkalinity) down below 70 ppm (our hot tub's current TA is 40 ppm), then get the PH adjusted between 7.4–7.7 before adding Chlorine to make the test valid as close as possible to apples to apples to the actual hot tub?

b) How much of 7.5% chlorine to initially add to, say ≈ 30 gallons of bath water to get an in-range chlorine level?

c) I only have a Taylor K-2106 'Bromine' test kit. Is there a workaround test that will tell me the effective Chlorine level I need to measure? If I can't do that with my K-2106 kit/reagents, what reagents would I need to buy to perform a proper Chlorine level test for our experimental bathtub test?

3) Are people with similar Bromine sensitivity able to completely avoid skin irritant sensitivity reactions of rashes and bumps by simply taking Antihistamines like: 25mg Benadryl or 10mg Cetirizine HCI (Zyrtec or Amazon Generic), 10 mg Loratadine (Claritin or Amazon Generic)? If so, what doses and how long before and after?


The Background:
We purchased a brand-new Bullfrog A6L (310 gals) Hot tub with the only time it was filled was at OEM water test at the time of manufacture, three months prior. The tub was purged, water balanced, Bromine Reserve added, Chlorine Shock done, PH & Bromine levels have been kept in range. It causes my wife extreme rash and bumps, but I have no skin reactions at all. Our initial soak (103º F, PH 7.6, Ttl Bromine 6ppm, TA 30 ppm) caused her an extreme skin irritation reaction where she had a rash and bumps on her trunk, arms and legs. I am using a Taylor K-2106 'Complete (FAS-DPD bromine)' test kit.

She said the pain and itching for a week was worse than her prior bout of Covid. It kept her awake all night. A week and a half later we let the Total Bromine drop to zero, PH ≈7.6, TA 40ppm. The water temp was only at 93º F. The skin irritation reaction was nowhere near as strong, but she still felt it coming on 1–2 hours after her soak. She took one Zyrtec 10mg Cetirizine HCI Antihistamine at that time and for two days following and the rash dissipated. I have had no skin irritation reactions at all.


Installation, thorough Purge and refill process:
Three weeks ago, after the brand new hot tub was installed, I filled it (310 gals) and did a purge using AHH!some. Ran jets on high w/ air for 30 mins. wiped away the green sludge from the shell above the water line and scooped a few small patches from the water. I then removed the four Bullfrog JetPaks and cleaned the green from them that was at the waterline. As an extra precaution, I then ran the jets on high for a second 30 minute period. There was only a small amount of green residue to wipe away this time. I then hosed ≈ 50 gallons of water into the tub via each jet to rinse any lingering residue of green biofilm and AHH!some purge. I siphoned out then used a shop vac to completely drain the foot well as well as vacuuming each JetPak supply pipe and all the lowest fixed jets. I have rinsed the filter once per week. I am pretty sure we can rule out ‘hot tub folliculitis’.

Thanks in advance for sharing what you did to be able for the allergic person to be able to enjoy the hot tub.
Dave

 

[AUSpool]

Geday Dave,

We have a history of allergies in our family and have had more consultations with allergy specialists than I care to remember. I have run our pool close to TFP recommended levels for over 10 years and our allergy sufferer has never had an issue. In fact it has been a go to first aid treatment with skin irritations. In the pool, or shower in winter and antihistamines (mostly Zertec). I run my pool at ~10% FC/CyA ratio. I feel your pain, I personally have never had issues with any pool or hot tubs but recently had a reaction to a hot tub in a ski resort rental. Red bump like rashes that came up a few hours after exposure that itched like heck. Zyrtec helped. The tub in question was managed with trichlor tabs. Probably with high CyA and over due for a water change. The second place we stayed at I had no reaction to that tub which was managed the same way. Back at home in our pool and haven’t had any reactions since.

I don’t do hot tubs but to answer your questions best I can;
1. No idea and I doubt anyone really does. True allergic reactions to chlorine are normally not chlorine, hypochlorous acid or hypochlorite but rather chloramines that are produced from the oxidation reaction of chlorine with nitrogen containing compounds like sweat. Chloranimes produce that classic “chlorine” smell, they are volatile and don‘t readily dissolve in water. Most literature says chloramines are responsible for bathe skin and eye irritations

2. I doubt you can. It would be very hard to maintain the conditions required for long enough to provide a useful comparison in a small volume of water. I suspect you will have to take a leap of faith, read through the hot tup sections and give chlorine the TFP way a go. Try running the tub cooler to start.

2. a&b I doubt you would need to adjust your alkalinity to attempt a test solution in a bath. The % is % of CyA concentration. I would try 10%, 80ppm CyA to 8ppm FC. The dosage's will be very small, a serial dilution will be your best bet, maybe even starting with liquid CyA. Use the old PoolMath page link from below to work out your amounts. Start with 1000 gallons and adjust your dilutions from there.

 

[Newdude]

So you're relatively new, but we do things pretty different here. Have a read : FC/CYA Levels.

Our TFP water is far less harsh than tap water. If your wife bathes and showers fine, she'll have no problems in a chlorine spa/pool on TFP.

 

[Mdragger88]

All the fc levels on this chart are equal in “active” strength at each cya level.
With zero cya you should aim for 2ppm fc to get an idea without risking it being too harsh.
Fwiw - my municipal tap water has around 3ppm fc in it. Yours might too. Tap water contains no cya. I wouldn’t fool with trying to manipulate ph or ta - I assume she takes showers & baths regularly and those don’t cause irritation.


Most bathtubs hold around 60 gallons or so of water when full.
You can use 5 gallon buckets for measuring to help be more precise. Then use PoolMath to calculate your dose.
Bromine is 2.25 x’s heavier than chlorine so when using a chlorine fas/dpd test you multiply the results by 2.25 to measure total br. I assume this means you can do the opposite with your kit to measure total chlorine. So basically if it reads 4ppm you have approximately 2ppm fc/tc.
Lots of folks have irritation with bromine. Have you used mps (non chlorine shock) in the tub? Its known to cause irritation as well.
I am no doctor but I do have a hivey kiddo & allegra is super helpful after the initial benadryl dose.
Sorry your wife has a reaction- hives are truly miserable.

 

[Davekro]

I just edited my original post to revise references of allergy/allergic to 'skin sensitivity' since my wife informed me her Dr. said she had a skin sensitivity reaction which is medically different from an allergic reaction, which is actually an immune system response, not a skin surface irritation.

 

[Davekro]

Geday Dave,

We have a history of allergies in our family and have had more consultations with allergy specialists than I care to remember. I have run our pool close to TFP recommended levels for over 10 years and our allergy sufferer has never had an issue. In fact it has been a go to first aid treatment with skin irritations. In the pool, or shower in winter and antihistamines (mostly Zertec). I run my pool at ~10% FC/CyA ratio. I feel your pain, I personally have never had issues with any pool or hot tubs but recently had a reaction to a hot tub in a ski resort rental. Red bump like rashes that came up a few hours after exposure that itched like heck. Zyrtec helped. The tub in question was managed with trichlor tabs. Probably with high CyA and over due for a water change. The second place we stayed at I had no reaction to that tub which was managed the same way. Back at home in our pool and haven’t had any reactions since.

I don’t do hot tubs but to answer your questions best I can;
1. No idea and I doubt anyone really does. True allergic reactions to chlorine are normally not chlorine, hypochlorous acid or hypochlorite but rather chloramines that are produced from the oxidation reaction of chlorine with nitrogen containing compounds like sweat. Chloranimes produce that classic “chlorine” smell, they are volatile and don‘t readily dissolve in water. Most literature says chloramines are responsible for bathe skin and eye irritations

2. I doubt you can. It would be very hard to maintain the conditions required for long enough to provide a useful comparison in a small volume of water. I suspect you will have to take a leap of faith, read through the hot tup sections and give chlorine the TFP way a go. Try running the tub cooler to start.

2. a&b I doubt you would need to adjust your alkalinity to attempt a test solution in a bath. The % is % of CyA concentration. I would try 10%, 80ppm CyA to 8ppm FC. The dosage's will be very small, a serial dilution will be your best bet, maybe even starting with liquid CyA. Use the old PoolMath page link from below to work out your amounts. Start with 1000 gallons and adjust your dilutions from there.

@AUSpool ,
Geday to you Steve as well,
Thank you for your detailed response! We may yet try the bathtub test, but after reading on a dermatology site that mentioned testing for allergies on patches of the person skin on their arm, we will ask her Dr. about that possibility first.
Several decades ago, I and a girlfriend at the time, her sister and sister's boyfriend spent a very fun three weeks driving from Sydney to Cairns to stay with friends of their for a bit in Cairns. Beautiful country, and you folks are the friendliest! Great time and great memories. My wife of 20 years is jealous of that trip. We may try to make it back down after I finally retire.
Best to you,
Dave

 

[Davekro]

So you're relatively new, but we do things pretty different here. Have a read : FC/CYA Levels.

Our TFP water is far less harsh than tap water. If your wife bathes and showers fine, she'll have no problems in a chlorine spa/pool on TFP.

@Newdude ,
By different, do you mean that TFP highly recommends a chlorine based hot tub specifically over using bromine for your hot tub sanitization?

When you say "our TFP water" do you mean a chlorine based hot tub, maintained with consistent weekly regularity, will not cause any skin sensitivity issues any more than tap water would? I could see that as reasonable for a swimming pool. Saying the same for a chlorine based hot tub kept at +/- 103º F, feels like a stretch. I read and watched the video in the link you posted that speaks of pools. Do you have a similar link that speaks to hot tubs?

I'm cautiously encouraged by what you say about changing over to a chlorine regimen from bromine. I will do more research on this.
Thank you for your response.

 

[Davekro]

All the fc levels on this chart are equal in “active” strength at each cya level.
With zero cya you should aim for 2ppm fc to get an idea without risking it being too harsh.
Fwiw - my municipal tap water has around 3ppm fc in it. Yours might too. Tap water contains no cya. I wouldn’t fool with trying to manipulate ph or ta - I assume she takes showers & baths regularly and those don’t cause irritation.
View attachment 556110
View attachment 556111
Most bathtubs hold around 60 gallons or so of water when full.
You can use 5 gallon buckets for measuring to help be more precise. Then use PoolMath to calculate your dose.
Bromine is 2.25 x’s heavier than chlorine so when using a chlorine fas/dpd test you multiply the results by 2.25 to measure total br. I assume this means you can do the opposite with your kit to measure total chlorine. So basically if it reads 4ppm you have approximately 2ppm fc/tc.
Lots of folks have irritation with bromine. Have you used mps (non chlorine shock) in the tub? Its known to cause irritation as well.
I am no doctor but I do have a hivey kiddo & allegra is super helpful after the initial benadryl dose.
Sorry your wife has a reaction- hives are truly miserable.

@Mdragger88 ,
Thank you for the response. I have only used 7.5% Chlorine (bleach) to activate the bromine, nothing else. Before we go trying to use her whole body as the test surface for a chlorine sensitivity test, any thoughts on a possible chlorine % solutions to apply to a small patch on her arm, maybe several times a day to see if chlorine causes an irritation response?
Thank you,
Dave

 

[Newdude]

By different, do you mean that TFP highly recommends a chlorine

We recommend levels that are outside of the norm. The industry shuns science and we listen to it, so basically their chemistry sucks. Normal pools/spas are terribly unsanitary and many have skin issues that didn't need to.

When you say "our TFP water" do you mean a chlorine based hot tub, maintained with consistent weekly regularity, will not cause any skin sensitivity issues any more than tap water would?

Correct. Pool or spa. Is less harsh than taking a shower.

Any irritations or noxious smells are from having too little chlorine 99 out of 100 times. I bump mine into the 20s for parties. (Which is entirely safe because of my 70 CYA........ again....... YAY science). Nobody has a clue. No nasty smells or red eyes to be found. Every last get together I *EVER* went to hurt my eyes.

Every last one.

And I smelled like chlorne for hours and maybe even the next day.

But yeah. We see it all the time. People don't have a chlorine aversion most of the time. They have an unsanitary pool/spa aversion that gives them 'hot tub rash'. (I forget the medical name but you can Google HTR). If they do have a chlorine aversion, they cant shower. We have yet to see one that i know of.

It seems some people do have a bromine aversion, but we are fundamentally a pool forum, where some have spas, but more of that select group uses chlorine. The bromine sample size isn't big enough to count for much.

 

[Bperry]

@Mdragger88 ,
Thank you for the response. I have only used 7.5% Chlorine (bleach) to activate the bromine, nothing else. Before we go trying to use her whole body as the test surface for a chlorine sensitivity test, any thoughts on a possible chlorine % solutions to apply to a small patch on her arm, maybe several times a day to see if chlorine causes an irritation response?
Thank you,
Dave

Some of the “industry standard” advice hasn't been updated since the 1960’s and so it can be common for people who didn’t know any better to be following those standards and having skin irritation caused by it. Read through the FC/CYA chart and get to know it really well.

 

[Mdragger88]

@Mdragger88 ,
Thank you for the response. I have only used 7.5% Chlorine (bleach) to activate the bromine, nothing else. Before we go trying to use her whole body as the test surface for a chlorine sensitivity test, any thoughts on a possible chlorine % solutions to apply to a small patch on her arm, maybe several times a day to see if chlorine causes an irritation response?
Thank you,
Dave

I truly don’t believe that’s necessary. If she showers or bathes at your house a properly chlorinated tub will be the same or less harsh.

 

[Mdragger88]

When you say "our TFP water" do you mean a chlorine based hot tub, maintained with consistent weekly regularity, will not cause any skin sensitivity issues any more than tap water would?

A spa is certainly different than a pool. The bather load is much much higher.
Any chlorine spa or pool should be maintained in some manner daily. At least fc & ph.
Once a week just doesn’t cut it for either. Nor does it in a bromine spa.

There’s no dedicated hot tub video but the same principles apply in regards to adherence of the
FC/CYA Levels & keeping fc above minimum at all times so nasties don’t grow. Many see chlorine as the enemy & try to keep it as low as possible- this is the opposite of what should occur. Don’t make that mistake.
Adequate chlorine in relation to cya in a chlorine tub/pool or (Total Br in a bromine spa) & maintaining proper ph (in the 7’s) keeps things sanitary & comfortable.
Inadequate chlorine (or Total Br) leads to irritation (skin & eyes), infections, rashes, algae & smells.
Improper ph leads to irritation (eyes, skin) & can do a doozy on your surfaces & equipment via scale or corrosion.
Every thing is in this guide

How do I use Chlorine in my Spa (or pool)?

If you have a question about any information within this Sticky, please start a new thread for yourself where you will receive very quick responses to your specific questions. Thank you! Introduction There are two main things to consider when maintaining your hot tub water, Water Balance and...

www.google.com

If you want some reassurance about chlorine- test your tap water.
Being as how your $10-$20k tub is currently unusable for her I would make the switch today.
They sell 99% dichlor @ Walmart for $25 for 2.25# - that amount lasts me for 2+ years in my tub.
You have everything else. Except the fc & cc reagents & the cya reagent r-0013 (you have the comparator but may need the correct squirty bottle)
These are what you need for fc & cc.

Until you get the reagents you can calculate your accumulated cya in
PoolMath
& use the workaround I mentioned above with your br reagent to measure fc.
All of these needed reagents, squirty bottles etc. are available on Amazon & tftestkits.net

 

[Davekro]

If you want some reassurance about chlorine- test your tap water.
They sell 99% dichlor @ Walmart for $25 for 2.25# - that amount lasts me for 2+ years in my tub.
You have everything else. Except the fc & cc reagents & the cya reagent r-0013 (you have the comparator but may need the correct squirty bottle)
These are what you need for fc & cc.
Until you get the reagents you can calculate your accumulated cya in
PoolMath
& use the workaround I mentioned above with your br reagent to measure fc.
All of these needed reagents, squirty bottles etc. are available on Amazon & tftestkits.net

Since it was going to cost me $47 for the three reagents, I bought the K-2006 Chlorine test kit refill on sale from TFtestkits.net . They don't say how long the USPS ground shipping will take. I still need a little squirt bottle. Any problem with using a Generic 1 oz squirt bottle ($8.99 4 Pk) and marking it at 7 & 14 ml, instead of buying (1)Taylor $7.99 #9191 empty squirt bottle with 7ml and 14ml lines?

I looked on the Walmart site and searched '99% Dichlor'. No particular product came up, so I assume that is the active ingredient in a product. What would I do with 'Product brand and product name (Dichlor?)' that contains 99% Dichlor? is that used to shock a chlorine spa (or pool) to activate chlorine? I have not had time to read up on how to start and test/monitor a chlorine set up hot tub.

[Edit 3/4/24: I realized I have these two 'dichloro' SpaGuard brand chemicals that were supplied with my spa purchase: Chlorinating Concentrate (Sodium dichloro-s-triazinetrione dihydrate 99%) and Enhanced Shock (Sodium dichloro-s-triazinetrione dihydrate 58%; Other Ingreds. 41.8%).]

Thank You,
Dave

 

[Davekro]

Correct. Pool or spa. Is less harsh than taking a shower.

We recommend levels that are outside of the norm. The industry shuns science and we listen to it, so basically their chemistry sucks. Normal pools/spas are terribly unsanitary and many have skin issues that didn't need to.

@Newdude ,
[Edit: correct my FC math off by a decimal from FC .03 to FC .3, and FC .08 to FC .8 respectively. Thank you @Bperry ]
What do you mean by less harsh than taking a shower? Are you saying a hot tub at your recommended level of (?) FC ppm is less than what you believe is in most city water? What are you assuming is 'normal' city tap water's Free Chlorine ppm? I tested our tap water today: cold water .8 ppm FC. Hot water (via an old 20 year old gas water heater) ≈ .3 ppm FC.
Assuming I raised my CYA from zero to 30 ppm, the mid-target would be 5 ppm. We are taking hot baths and showers in city water with ≈ .3 ppm FC, setting a hot tub at 5.0 ppm would be 17 times more ppm than our bath water. I have no idea if 17 times our tap water's FC level would cause my wife's skin sensitivity to cause rashes or not. But our tap water most definitely has significantly less FC than my hot tub would have, using the 5 ppm FC from the Liquid Chlorine chart as a target. Am I missing something here?

Your apparent assumptions of my city water being somewhere north of 3, 5 or more ppm FC seem to be way off.

I have a read : FC/CYA Levels.
(My tap water has zero CC or CYA.)

 

[Bperry]

@Newdude ,
1) What do you mean by less harsh than taking a shower? Are you saying a hot tub at your recommended level of (?) FC ppm is less than what you believe is in most city water? What are you assuming is 'normal' city tap water's Free Chlorine ppm? I tested our tap water today: cold water .08 ppm FC. Hot water (via an old 20 year old gas water heater) ≈ .03 ppm FC.
The Taylor Pool & Spa Water Chemistry booklet for hot tub recs. 2 ppm min, 2-4 ppm Ideal, 5 Max. We are taking hot baths and showers in city water with ≈ .03 ppm FC, setting a hot tub at 3.0 ppm would be 100 times more ppm than our bath water. I have no idea if 100 times our tap water's FC level would cause my wife's skin sensitivity to cause rashes or not. But our tap water most definitely does not have more FC than my hot tub would have, using (I assume by your reference is too low)Taylor's middle rec. of 3.0 ppm of FC.

2) Cryptics aside, what free chlorine level do you personally or the TFP forum specifically recommend for hot tubs that differs from an industry standard that you do not specify either? Sorry if I seem abrupt, but your apparent assumptions of my city water being somewhere north of 3 or more ppm FC seems way off.

You can’t measure FC of 0.03 or 0.08 with a Taylor kit so that would be a question to clarify. He is talking about the amount of active HOCL. When you add CYA to the water the amount of active chlorine is reduced but still registers in the test process though it’s inactive but in reserve when needed.

When using the TFP FC/CYA chart with a CYA of 50ppm, I run the FC around 6-8ppm for swimming. In that case, the amount of “active” HOCL is less than that found in tap water with zero CYA and 3ppm of FC. The industry recommendations don’t take that into account with the 3ppm max FC level recommendations.

 

[Davekro]

All the fc levels on this chart are equal in “active” strength at each cya level.
With zero cya you should aim for 2ppm fc to get an idea without risking it being too harsh.
Fwiw - my municipal tap water has around 3ppm fc in it. Yours might too. Tap water contains no cya. I wouldn’t fool with trying to manipulate ph or ta - I assume she takes showers & baths regularly and those don’t cause irritation.
View attachment 556110
View attachment 556111
Most bathtubs hold around 60 gallons or so of water when full.
You can use 5 gallon buckets for measuring to help be more precise. Then use PoolMath to calculate your dose.
Bromine is 2.25 x’s heavier than chlorine so when using a chlorine fas/dpd test you multiply the results by 2.25 to measure total br. I assume this means you can do the opposite with your kit to measure total chlorine. So basically if it reads 4ppm you have approximately 2ppm fc/tc.
Lots of folks have irritation with bromine. Have you used mps (non chlorine shock) in the tub? Its known to cause irritation as well.
I am no doctor but I do have a hivey kiddo & allegra is super helpful after the initial benadryl dose.
Sorry your wife has a reaction- hives are truly miserable.

@Mdragger88 ,
[Edit: correct my FC math off by a decimal from FC .03 to FC .3, and FC .08 to FC .8 respectively. Thank you @Bperry ]
Starting with zero CYA in our tap water and .3 ppm FC (zero CC of course), 2 ppm would be 7 times more ppm of FC than my tested tap water. I don't know if 7 times our tap water's FC level would cause my wife's skin sensitivity to cause rashes or not. But our tap water has much less FC than my hot tub would have, using the 2 ppm FC (w/ zero CYA).

I was ready to purge and drain my tub today, until I realized the tap water we are showing in has .3 ppm FC. Does FC of 2 ppm have a much less skin irritation factor than say 4 ppm at a CYA of 50 ppm? Meaning, does a higher CYA (50) somehow make a relatively higher FC level (4) equivalent in skin irritation level to FC (2) at zero CYA. I'm guessing no, that a higher FC level no matter what, has increased potential for sensitive skin to become irritated.

I will have her do a bathtub test with 2 ppm FC. That would be the bare minimum FC level at zero CYA. If she does not get a rash reaction from 2 FC at zero CYA, I guess the next test I should have her do is at 5 ppm (at zero CYA), that being the high end of the recommended range. Then even test at 7 ppm FC because sometimes FC levels might be a bit higher than the target, but we still want to know if this elevated level is still non-reactive for her.

 

[JoyfulNoise]

….. I have only used 7.5% Chlorine (bleach) to activate the bromine, nothing else….

This could be an issue. Current laundry bleach formulations almost all exclusively license and use “Fabric Protection Technology” that was developed by Clorox Corporation (they call it ChloroMax Technology). It’s a potent and oxidation resistant surfactant that is added to the bleach that leaves behind a residue on surfaces that makes it harder for dirt and pathogens to stick to. Your wife’s skin may have become sensitized to it and that caused the painful rash to develop.

Just a thought …

 

[Davekro]

You can’t measure FC of 0.03 or 0.08 with a Taylor kit so that would be a question to clarify. He is talking about the amount of active HOCL. When you add CYA to the water the amount of active chlorine is reduced but still registers in the test process though it’s inactive but in reserve when needed.

When using the TFP FC/CYA chart with a CYA of 50ppm, I run the FC around 6-8ppm for swimming. In that case, the amount of “active” HOCL is less than that found in tap water with zero CYA and 3ppm of FC. The industry recommendations don’t take that into account with the 3ppm max FC level recommendations.

Oops, my math was off by a decimal!
I did the Taylor test for Free & Combined Chlorine (FAS-DPD) because the Taylor K-2006 Chlorine test kit does not include R-0001 to do the DPD test.
I used a 25 ml sample; + 2 dippers of R-0870; the 1st drop of R-0870 turned the very weak pink sample to what 'looked like' clear, but "maybe" had the slightest hint of color left, but maybe not, The second drop turned it clear for sure. I estimated the half drop, or less, after the first drop would have turned it just as clear. I rounded to 1.5 drops. 1.5 drops x the .2 /drop factor = .3 ppm FC.

You can’t measure FC of 0.03 or 0.08 with a Taylor kit so that would be a question to clarify. He is talking about the amount of active HOCL. When you add CYA to the water the amount of active chlorine is reduced but still registers in the test process though it’s inactive but in reserve when needed.

When using the TFP FC/CYA chart with a CYA of 50ppm, I run the FC around 6-8ppm for swimming. In that case, the amount of “active” HOCL is less than that found in tap water with zero CYA and 3ppm of FC. The industry recommendations don’t take that into account with the 3ppm max FC level recommendations.

@Bperry ,
Thank you for catching my math error being off by a decimal. Dooh! I edited my above two posts to Newdude and Mdragge88.
I assume the Taylor recommendations in their booklet on page 41 are under the industry rec. Page 41 recs. for IG pool 2-4 ppm, 4 ppm Max. For Spa 2-4 ppm, 5 ppm Max. Lower in the chart on that page it recs CYA of 30-5o, 100 Max. But it does not show any FC range differences for varying CYA levels. I guess that is where their recs. for FC range becomes less valid.

I will have to read up on HCOL. Thanks for pointing me to that variable or aspect of the chemical interactions. And thanks again for pointing out my math error. )

 

[Davekro]

This could be an issue. Current laundry bleach formulations almost all exclusively license and use “Fabric Protection Technology” that was developed by Clorox Corporation (they call it ChloroMax Technology). It’s a potent and oxidation resistant surfactant that is added to the bleach that leaves behind a residue on surfaces that makes it harder for dirt and pathogens to stick to. Your wife’s skin may have become sensitized to it and that caused the painful rash to develop.

Just a thought …

@JoyfulNoise ,
I have been using Clorox Disinfecting bleach to date to activate the bromine in my bromine hot tub. It has the "With ChloroMax Technology" gold and blue label on it. I have a gallon of Home Depot's house brand Concentrated Germicidal Disinfecting Liquid Bleach Cleaner
7.5% Sodium Hypochlorite [Contains No Phosphorus]. My 'version' of HDX bleach has a picture of a mop and bucket and has no Chloromax label, nor any mention of 'Fabric Protection' like the HDX version that has a laundry basket w/ towels that says 'Fabric Protection'.
If I were so lucky that this gallon I have of HDX bleach does not in fact have the CloroMax or 'Fabric protection', and I started using it instead of the Clorox (or any other) w/ Chloromax, would the ChloroMax additive remain in the tub until the next purge, drain, refill? Or would it dissipate out as soon as I started using the new HDX bleach w/o ChloroMax?

What do you think the possiblity of my wife's skin sensitivity may be to the small amounts of ChloroMax bleach added since my first fill a month ago, versus a skin sensitivity to Bromine?

I was ready to do a bathtub test with chlorine bleach to test my wife's skin sensitivity to chlorine. With the idea of possibly changing from a Bromine tub to a Chlorine tub. I'll now certainly use the HDX version that mentions no Chloromax or 'Fabric Technology', just in case that is a factor. Is there any way to narrow down what in my current hot tub is causing her skin sensitivity? I felt pretty good that the single AHHsome! purge did the job when installing this new Bullfrog tub that was built (hence water tested) in October 2023. Now I am thinking, though it has only been one month, it may be worth purging and draining again soon. Then the decision to try chlorine, I guess, instead of Bromine. I had Ahhsome's Aqua Clarity from day one but did not start adding my first 'weekly dose' until week three. That brought out a tiny bit of green, now making me wonder if another, one month later AHH!some purge might be called for... That bio film might be her skin sensitivity?? Could this be, even, that the total Bromine level has always been maintained within range?

Thank you for any thoughts, sir.

 

[bradgray]

@Davekro I won't bother to regurgitate the great advice given here, other than to reaffirm liquid chlorine is the best method and soften your hesitiation. No alternative or exceptions if you were to ask me.

If you're not convinced, perhaps I can sway you with statistics. If you just count our spas, my team makes over 3,500 service stops a month for tubs used by tens of thousands of people a year. We use 12.5% sodium hypochlorite liquid and 1" trichlor tabs in moderation. Nothing else other than ash and bicarb. It works brilliantly, and it's the best method I've used over the course of a decade and a pretty large test group.

I'll even go as bold to state the only time we ever get a report about a rash is when we have combined chlorine. Without exception when we test a spa with this report, we have stark divergence between TC and FC. This is the catalyst for discomfort described above in reference to chloramines. In rentals, it's usually from kids relieving themselves or sports groups skipping the shower beforehand

I can also count on one hand how many times we've used a purge chemical. If you keep the sanitizer on target and don't muddy the chemistry with all the fluffy spa dealer products, it's really very easy.

We love spas. Most of my industry hates them.

(Last note - we hate bromine. But I'll save you the diatribe.)