SPA & SWG: chlorine 6 ppm/day and rash!

[presse55]

Hello!

I've had the tub for 2 months now, and started getting a rash 10 days ago.

Details:

• Drained water 3 weeks ago after 'flushing/cleaning' for 24 hours;
• Shocked to 10 ppm after refilling and once again 10 days later;
• Water is crystal clear and never got murky in that period;
• Have had no need for MPS;
• See signature for chemistry as of today;
• I measured chlorine PPM at start & end of a 30 minute SWG cycle:
  Start: FC 4 ppm;
  End: FC 5 ppm;
  CC: 0 ppm;
• So I conclude the SWG adds 1 ppm per 30 minute cycle;
• I've been bathing most days, once, for 30 to 45 minutes;

Questions:

• This suggests (correct me please!) the SWG adds 6 ppm per day, since it runs 6 cycles per day;
• Does this look right?
• I have not carried out an OCLT;
  Should I, to determine if I have something brewing?

I have a very 'low grade' rash (only over ribs and lower back) which gets a bit worse after bathing, and partly subsides over the next 24 hours. Hubby has no reaction, but has been bathing a bit less than me;

Thanx in advance!

 

[pooldv]

In almost all cases a rash from a hot tub is caused by bacteria. Bacteria thrive in warm water. Bacteria grow quickly in low to no chlorine situations and then it takes more chlorine to kill it. After soaking add bleach/chlorine to 10 ppm or so, pump running and test in 30 minutes. This will help determine your "normal" person/hour use of chlorine. Then test again before the next soak to make sure FC isn't 0. The goal is to add/make enough FC so that it never gets below minimum for your CYA, [FC/CYA][/FC/CYA].

Numbers look good. Your SWG theory is only correct if there isn't anything in the water consuming FC during your test. Most SWG owners manuals will list the amount of chlorine gas produced by the cell. PoolMath Effects of Adding Chems will tell you how many ppm that is in your tub.

This page is also helpful in managing a hot tub, How do I use Chlorine in my Spa (or pool)?

 

[jeffchap]

Check your pH. Very high or very low pH can cause skin irritation. My spa tends to get very acidic (low pH).

 

[Brian VT]

Hello!
I've had the tub for 2 months now, and started getting a rash 10 days ago.
Details:

• Drained water 3 weeks ago after 'flushing/cleaning' for 24 hours;

How did you 'flush/clean' ?
Chlorine is not able to remove biofilm. You may have some in your plumbing.
Many here suggest a product called Ahh-Some. I'd suggest using this and then drain/replace your water.

 

[presse55]

Thank you for the responses.

The pH has been stable for several days now at 7.5

Prior to draining and refilling, I used a product (Canada) called DrainPrep. Basically an enzymatic treatment against biofilm in the plumbing.

 

[Isaac-1]

If possible I would also suggest getting Ahh-Some for hot tubs, jetted tubs (note they make a number of Ahh Some products, filter cleaners, etc. so you want to get the right one. It seems to be MUCH more effective than other hot tub cleaning chemicals.