Effects of High/Low Hot Tub pH

hot tub waterAre you experiencing scale build up, cloudy water, or having trouble keeping your sanitizer levels where they should be? How about itchy dry skin or burning eyes after using your hot tub? All of these and other issues could be caused by pH outside of the recommended range.

It is important to keep your pH levels between 7.2 and 7.8 on the logarithmic pH scale which ranges from 0.0 to 14.0. Having pH levels that are higher than 7.8 or lower than 7.2 can cause problems for your and you hot tub.

High pH is a common cause of calcium and scale build up at your hot tub water line and cloudy or dull water.  It also causes bathers to often experience itchy skin and burning eyes.  Keeping your hot tub sanitizer levels where they should be is also very difficult when your pH is too high, along with clogging of your filter media and elements.

Low pH may cause corrosion of metal hot tub parts like you heater element, and staining due to the metal corrosion. Like with high pH bathers will experience itchy dry skin and burning if the eyes and nose. Low pH will breakdown swimwear and hot tub accessories, and causes rapid dissipation of hot tub sanitizer like chlorine requiring more frequent dosages to keep the levels correct.

To avoid the issues cause by pH that is too high or too low it is important to test your hot tub water frequently with a water test kit or test strips and make adjustments when needed.

If you do encounter a problem with high pH, use a pH down product to get it back within the correct range.  If your pH is too low, use a pH up product to raise the pH. Keeping your hot tub’s pH levels in check will create a more comfortable environment for your bathers, help you avoid scale and calcium buildup, and help keep your hot tub equipment free of corrosion.
Spazazz RX Spa Aromotherapy


Kasey (Staff)
October 10, 2016

Hi Gavin,

A couple things to consider: pH tends to rise with use, so the more people in the spa the more it will increase. It is far more common to reduce the pH on a regular basis than it is to decrease it. As far as the test strips go, make sure neither of them are expired. Reading a test strip is somewhat subjective since the colors may look different from person-to-person, but they should give you a pretty good idea of where your spa chemicals are at.

Angie Treasure
December 29, 2014

John, there’s a good chance that you’ve developed a case of hot tub rash, likely from poor sanitizer levels and/or high pH. It sounds like their pH reading may have been a little high. In the future, you can use the smell and eye test to judge whether or not a hot tub is safe to get into. If a hot tub has foaming, has a harsh or moldy odor, or buildup along the tiles, it’s not worth getting into. However, if high pH is the issue, it may be difficult to judge sight unseen. If you have test strips available to you, it may not be a bad idea to take along with you. The pH levels of the water should be between 7.2-7.8, preferably somewhere in between if you’re having a reaction to 7.8.

Angie Treasure
December 29, 2014

If you have a bad case of hot tub rash (which it sounds like you do), try using a cold compress on the affected areas. You can also try and disinfect the rash with a vinegar or rubbing alcohol. Anti-cortisone cream can be helpful to keep the itching at bay. If the rash doesn’t seem to be getting better and starts to spread, you may need to see your doctor and obtain some antibiotics. Good luck!

Gavin Whittaker
September 1, 2016

Help! My home hot tub seems clean, smells good, looks good and I work hard to keep it that way BUT I use 2 different types of test strips and one reports v.high PH whereas the other below OK PH…mixed readings, I’m confused and yet TA is OK. Not sure which PH Chemical to put in….used it last night (2 people) and PH increased. Is that normal? Thanks

John Aresco
December 28, 2014

I went to 24 fitness today and as little as 10 min or less I started to notice my arm pits burning from sitting in their spa, after I got out, I notice that my feet, legs back hips and some other parts are red with some white spots like blisters. Now my skin is burning and itching. They checked the ph and said it was at 7.8, they added some extra water, but what is the best way for me to avoid this from happing again besides not useing the amenity. I was thinking maybe I should bring my own test strips and check it before entering.

John Aresco
December 28, 2014

What should I use to get my skin to stop burning and itching from being exposed to a high ph in a spa, the maintance person said to rinse off real well, I have rinsed off and showered twice and my skin is still irratated.thanks

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