Total Alkalinity for Swim Spas

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Ideal Total Alkalinity Range for Swim Spas: 80-120 ppm

Test your swim spa’s Total Alkalinity level at least twice a week, with a test kit or strips. We also recommend taking a water sample to a dealer test station periodically (once a month) to verify results.

If you use FROG®  @ease® Sanitizing System for Swim Spas, use only FROG @ease Test Strips to dial in the low chlorine level FROG needs. Other test strips can cause you to over-chlorinate, which can cause confusion and waste money by adding too much chlorine.

What is Total Alkalinity?

Total Alkalinity describes how “buffered” the water is against sudden changes in your hot tub’s pH. The alkalinity of your hot tub is perhaps the most important water balancing step in your hot tub to manage and should always be the first thing you test before adding chemicals, including FROG® products, into the hot tub. The ideal range for your hot tub’s alkalinity level should be between 80-120 ppm (parts per million). If you are unsure if your water is adequately balanced, our Langelier Saturation Index (LSI) Calculator can tell you.

Note: You can have technically balanced hot tub water, as measured by the Langelier Saturation Index (LSI), even if your Total Alkalinity levels may be a little high or low.

Low Total Alkalinity

Just as low pH and low Total Hardness levels can be damaging to your swim spa, so can having a low Total Alkalinity level. While a low Total Alkalinity level may not be immediately noticeable on swim spa equipment and surfaces, a low Total Alkalinity level will often drive the pH level down, turning the swim spa water more acidic, which results in itchy dry skin and irritated eyes.

Additional problems associated with low Total Alkalinity in swim spas include

  • Pitting, etching, cracking and delaminating of swim spa walls and surfaces
  • Corrosion of metal surfaces in or around your swim spa (for example, heating elements, pump seals, internal parts on gas fire heaters, pipes, etc.), It can also result in stained swim spa walls.
  • Swim spa sanitizers (chlorine particularly) are less effective with low Total Alkalinity. To achieve the same sanitizing effect when Total Alkalinity is low, you’ll need to add more sanitizer
  • pH bounce (when a swim spa’s pH level quickly fluctuates up and down

How to Raise Alkalinity in a Swim Spa

Before you begin to adjust the Total Alkalinity, know how the volume of water (in gallons) your swim spa holds. The idea Total Alkalinity level is between 80-120 ppm. If you are unsure of how big your swim spa is, use our Spa Volume Calculator to help

You can increase your swim spa’s Total Alkalinity in two ways: 1. Use sodium bicarbonate (baking soda) or 2. Any type of alkalinity increaser product.

If you choose an alkalinity increaser product be sure it’s  made from sodium bicarbonate, which is the main substance used to raise pH.  As always, after adding the sodium bicarbonate (baking soda) or alkalinity increaser, let the swim spa sit for at least 6 hours before retesting.

High Total Alkalinity

While high Total Alkalinity levels are not as damaging to your swim spa as low Total Alkalinity levels, it’s still important to keep the Total Alkalinity balanced to prevent unplanned maintenance costs and prolong the life of your swim spa filter, pipes and other equipment

The most common problem swim spa owners experience with high Total Alkalinity levels is cloudy/ murky water because swim spa water with high Total Alkalinity allows particles to more easily come out of solution (i.e substances float freely in the water). Many other swim spa water issues associated with high Total Alkalinity stem from this dissolution, including

  • Water scaling on swim spa surfaces and equipment
  • Reduced water circulation due to clogged pipes and filters as particles come out of solution; they float freely in the water and are deposited on things the swim spa water comes into contact with (i.e. scaling)
  • Clogged filters
  • Higher water pressure; as pumps become clogged and pipes narrow with scale they are forced to run harder, resulting in cracks and reducing their lifespan
  • pH lock; changes to the swim spa water’s pH level are resisted due to the high Total Alkalinity level in the swim spa

How to Lower Alkalinity in a Swim Spa

  • The two most popular chemicals available to help you lower the Total Alkalinity in your swim spa are muriatic acid and sodium bisulfate (also known as dry acid).
  • After you’ve added muriatic acid, dry acid or another alkalinity decreaser product, check the pH level in the swim spa, as the pH level may have dropped as well.

Simplify your swim spa water care! FROG® @ease® Sanitizing System for Swim Spas kills bacteria 2 ways with FROG Minerals and a low level of chlorine for Cleaner, Clearer, Softer and Easier® water. FROG also helps maintain pH levels to keep your water balanced.