Alkalinity question

[wrainka]

Hi

We are fairly new owners having had our tub about 5 months. We have our water tested monthly by our dealer and consistently have to add alkalinity increaser in what I think is a large amount. If I add weekly according to the test strips the water test from the dealer tells us the alkalinity is 40-60 ppm and our dealer recommends 125-150 ppm so we are adding quite a bit. They recommend adding more than the test strips would indicate during weekly maintenance.

We recently purchased an Aquacheck monitor as I was unhappy with the test strips. So using the meter I now keep the alkalinity in the 100-120 range. The dealer recommends 125-150 while the Aquacheck literature recommends 80-120. When I questioned the dealer about these different recommendations the dealer said to keep it around 120. In the last 2-3 months since I have been keeping these levels as close to 120 as possible my husband has noticed some slight skin irritation. The first few days after maintenace he notices a bite/tingling to his skin while using the tub. He has also developed a sort of rash - dime sized red blotches on his legs, arms and back. He has been to the dr who has ruled out folliculitis and said it resembles an allergy. He was prescribed a steroid cream and will go back in a few weeks. If there is no change his dr will refer him to a dermatologist. After a few days the skin irritation goes away until the next maintenance then it resumes again. The weekly maintenance has been the same since we first purchased the tub with only the alkalinity levels changing which leads us to rule out the other chemicals as the irritant.

My questions -

- has anyone experienced any sensitivity to alkalinity levels?
- what level of alkalinity is recommended to ensure no damage to the lines, jets, pumps etc of the tub?
- any other thoughts on what could be causing the skin irritation?
- other suggestions??

Thanks.

[SerjicalStrike]

What are you using for sanitizer and how often are you using it?

[TwinCitiesHotSpring]

alk acts as a buffer for pH so depending on what you keep your calcium levels at you want to find the "perfect range" I prefer to keep calcium levels on the lower side (mid to high 100's) and run alk right around the 60-80ppm range which helps prevent constant pH "creep/rise"

as stated above what are you using for sanitizer? I know heavy doses of MPS/Shock in particular can cause many skin problems/allergies for many people.

[wrainka]

We use chlorine for a sanitizer. We have the Spa Synergy system that came as the startup kit. We add chlorine tablets to a dispenser in the filter. The dealer has recommended 3 tablets at the weekly maintenance. At that time we also check and adjust ph and alk levels, add a stain and scale liquid and a water conditioner along with a premix called Clear. This doesn't sound like the system that I have read most people using on here so not sure if it will answer any questions.

Since we got the tub we have been doing everything that we are now  except now we are keeping the alk levels higher so that is why we are thinking that might be the cause of the skin irritation.

[chem geek]

It sounds like the chlorine tabs you are using are probably Trichlor pucks, which is surprising since those are not usually used in a hot tub since they are very acidic and usually dissolve too quickly.  If that is indeed what you are using, then that is why the TA recommendation is higher since that helps prevent the pH from rising too quickly.  The Trichlor will lower the TA over time which is why you need to add more.  For every 10 ppm Free Chlorine (FC) added by Trichlor, it lowers the Total Alkalinity (TA) by 7 ppm.  I do not believe the higher TA is causing your skin irritation.

HOWEVER, for every 10 ppm FC added by Trichlor, it also increases the Cyanuric Acid (CYA) level by 6 ppm so depending on your spa use the CYA level could be quite high if you haven't been changing the water frequently.  A higher CYA level will reduce chlorine's effectiveness so if your FC tends to be low or ever gets to zero then you could have Pseudomonas aeruginosa growing in your tub -- the bacteria that causes "hot tub itch".  Look at the chart in this link and see if your skin irritation is bacterial or chemical based.

[wrainka]

I have checked our sanitizer and it is trichlor as you thought. I am a bit confused why this system would be recommended by our dealer - maybe the difference between US and Canadian practises??

We have had this water since Nov 1 and were planning on changing in the next few weeks as recommended by our dealer. I have noticed we are going through the tablets more quickly in the last few weeks even though our usage is about the same.

Two thoughts I have on your idea though:
-this skin irritation began within a month of the water change when we were not keeping the alk levels as high as now.
-if this is bacteria related and not chemical why is it just my husband being affected and not me?

Thanks for your help so far.

[clover]

The ONLY chlorine that is suitable for a Hot Tub is Di-Chlor which is granular and administered daily when needed, all other chlorines are verbotten in a Hot Tub.  Your sensitivity problems are the chemical stew you are sitting in.  Tri-Chlor is 2.6 on the pH scale, and liquid chlorine is 13.0 on the pH scale.  Both are POOL CHEMICALS and are not suitable for Hot Tubs.  You skin is pH neutural 7.2 to 7.6 range and the sensitivity reaction is chemically induced on the bather.

Dump the Tri-Chlor, get an ozonator, and use granular chlorine as needed. 

[chem geek]

The use of Dichlor-only will not lower the pH (or TA) as much as Trichlor, but it will build up CYA even more quickly.  Though Dichlor-only is the most popular approach, another is to use Dichlor initially for about a week or so to build up to around 30 ppm CYA and then to switch to bleach (details described here).  However, for this latter approach, one must have the TA be very low (50 ppm or so) and it is also helpful to use 50 ppm Borates (Proteam Gentle Spa).  The water generally lasts twice as long with this approach.  The downside to both Dichlor and Dichlor-then-bleach is that you have to add chlorine every day or two.  I suspect the dealer recommended Trichlor for the greater convenience, similar to recommending bromine tabs except that as was pointed out Trichor is not normally used in a spa because it usually dissolves too quickly in hot water (i.e. will make chlorine levels too high) and is very acidic.

6% Clorox Bleach has a pH of 11.9 (not 13 -- high quality 12.5% chlorinating liquid has a pH of 12.5).  However, chlorine usage/consumption is an acidic process (details in this post) so the primary source of pH rise is from carbon dioxide outgassing which is why the TA must be kept very low if using bleach in a spa.  I use 12.5% chlorinating liquid in my pool yet I only add a small amount (a couple of cups) of acid every month or so -- if the high pH of the chlorine were not offset by the acidity of chlorine usage/consumption, I would have to add cups of acid every week.

As for skin irritation, everyone reacts differently since some have more sensitive skin.  It is not uncommon to have only some people in a tub get a reaction from either chemicals or bacteria.  It is also possible that the irritation is heat-related.

Have you been monitoring the chlorine levels and if so, how?  Test strips are next to useless for most measurements.  Drop-based tests are better.  A good test kit is the Taylor K-2006, but it's very expensive in Canada.  You could get a Taylor K-2005 instead, but the DPD chlorine test will bleach out at higher chlorine levels (this also happens with common test strip tests) making you think you have no chlorine when you actually have too much.  Based on your using Trichlor, I would not be surprised if the chlorine level got too high and the pH too low, unless you were carefully monitoring both.

How often were you using your spa -- how many people soaking for how long for how many times per week?  Also, what is the size of your spa (in gallons or liters)? The standard Water Replacement Interval (WRI) = (1/3) x (Spa Size in U.S. Gallons) / (# of bathers) where soak times are assumed to be around 20 minutes.  With Dichlor-then-bleach, one can usually go around double this time.

[wrainka]

Chemgeek I really appreciate your knowledge and am even more confused now.

We have a J-355 and it holds 453 us gallons. There are 2 of us using it about 4-5 times per week for 20-30 min per soak. We have an Aquachek meter to test the water. Our chlorine levels are usually quite low - 1-3 ppm which the dealer tells me is ok. The ph is usually in the 7.4 - 7.6 range - alk has been my only frustration - until now. My chlorine was lasting the whole week until a few weeks ago and now isn't.

I am quite confused as to why the dealer only sells this Spa Synergy system if it isn't recommended for hot tubs. I am not even sure where to buy the chemicals you have recommended here in Canada. The other issue I have is I don't want to void my warranty by not following the instructions of the dealer.

Thanks again for all your help.

[chem geek]

I assume you are referring to this Spa Synergy system.  So long as your pH is staying within range and the chlorine level is fairly stable, then you're OK and I'm not saying you should void your warranty.  Just note that the TA will drop over time so you'll be adding baking soda (or their Alkalinity Up product which is the same thing, but more expensive) regularly.  Because the Trichlor is so acidic, that is why they want you to keep the TA higher so that the pH will tend to be more stable.

2 people 4-5 times per week for 20-30 minutes is a moderate bather load because your spa is larger than average (which is around 350 gallons) so the WRI would be around (1/3) x 453 / (4/7) = 264 days to (1/3) x 453 / ((5/7)*(3/2)) = 141 days, so your getting 5 months (150 days) of usage before the water is starting to turn and the chlorine demand has gone up is about right as far as needing to change the water.  Also, if your tub is new, your first fill won't last nearly as long since there can be leftover oils and other organic materials in a new spa (not to mention biofilms from wet testing).

If this is a new tub and you didn't decontaminate it to start with, then I'd suggest you do that for your next fill.  Use Spa System Flush if you can get it.

As for chemicals, TA is not an irritation (it's just bicarbonate of soda); it must be something else.  You say your husband gets these symptoms right after the weekly maintenance.  What exactly is being added for that maintenance?  I'll bet there is something else other than baking soda adjusting the TA.  Maybe there is a non-chlorine shock as that is a known irritant.  That might be part of Spa Synergy Clear.  You could try simply not using that since it's not really necessary if you consistently maintain proper chlorine levels, at least for the first 2-3 months.  After that with Trichlor, the higher CYA levels that build up do require something else to help oxidize bather waste, but unless you are willing to use a different system, you'll just have to change the water more frequently or finding something else as a weekly shock that isn't irritating -- perhaps enzymes instead of non-chlorine shock.

[paulsimmons]

The ONLY chlorine that is suitable for a Hot Tub is Di-Chlor which is granular and administered daily when needed, all other chlorines are verbotten in a Hot Tub.  Your sensitivity problems are the chemical stew you are sitting in.  Tri-Chlor is 2.6 on the pH scale, and liquid chlorine is 13.0 on the pH scale.  Both are POOL CHEMICALS and are not suitable for Hot Tubs.  You skin is pH neutural 7.2 to 7.6 range and the sensitivity reaction is chemically induced on the bather.

Dump the Tri-Chlor, get an ozonator, and use granular chlorine as needed. 

Agreed.  I also agree with Chem geek that your husband might be reacting to something in the spa synergy cleaner.  In my humble opinion, it sounds like there's a lot of stuff being added on a regular basis that might not be necessary and could be causing some issues. 

wrainka - you also mentioned not being sure where to purchase some times you might need.  Give this store a try: spa chemicals - I've had good luck with them.