High/Low Alkalinity in Your Hot Tub

As the measurement of buffering capacity in your hot tub water, Alkalinity, plays an important role in your water balance. Alkalinity should ideally be maintained between 125-150 ppm (parts per million), however if you use a chlorine or bromine sanitizer levels are still okay up to 200 ppm. If you use a biguanide sanitizer levels should never be above 170 ppm. When alkalinity is allowed to rise or drop below these levels it can cause significant water problems and problems for your spa.


High Alkalinity

When total alkalinity levels are too high, water problems such as scale build up and cloudy water are likely to occur. As alkalinity acts as a buffer for the pH in your water, high alkalinity levels usually mean high pH levels also. This can cause skin and eye irritation in your bathers and your sanitizer will be less effective.

The way to combat high alkalinity and bring it back into the proper range is to use a pH decreaser such as Spa Pure pH Down or ProTeam Spa pH Decreaser.  Even if you pH is not high this product can be used to lower alkalinity then simply bring ph back up with a pH increasing product.

Low Alkalinity

Alkalinity that has dropped below recommended levels can cause corrosion of metals and equipment in your spa, skin and eye irritation, and rapid changes in your pH levels.

If your alkalinity is low but your pH levels are within the recommended range using Spa Pure Alkalinity Increaser or Proteam Spa Alkalinity Up should return your levels to normal after dosing instructions are followed.

If your pH is also low you will want to use a ph Increase to bring pH up first and then finish off balancing the water with an alkalinity increaser.

As always the best way to maintain balanced water is to test often with a water test kit and make adjustments as needed. Frequent testing and balancing should keep any problems from getting out of hand and causing serious problems in your hot tub. If you ever have any questions about water balancing or your hot tub, please contact us.
Spazazz RX Spa Aromotherapy


Sheila Heitt
October 22, 2015

My ph is always high. My alkalinity is normal. But when I try to lower my ph my alkalinity lowers and my ph doesn’t. What do I do?

Kasey LaRose
April 19, 2016

In a hot tub, the pH always tends to be on the rise due to the bodies soaking in it, so it is not uncommon to have to lower the pH frequently. The chemical you are using to lower the pH will also lower the alkalinity. In my experience, when the alkalinity becomes too difficult to manage, it’s usually a good time to drain and refill with new water. This usually happens around the 3 or 4-month mark.

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