The Relationship Between pH & Total Alkalinity
Many pool owners struggle with fluctuating pH because they view pH and Total Alkalinity (TA) as separate parameters. In reality, Total Alkalinity is your pool’s carbonic acid buffer system. It acts as an anchor that prevents wild swings in pH.
If your TA is too low (<60 ppm), your pH will swing rapidly with rainfall or swimmer usage. If your TA is too high (>130 ppm), it continually pulls your pH upward, creating a relentless cycle of acid additions.
How to Safely Dose Muriatic Acid
- Wear PPE: Always wear safety goggles and chemical-resistant gloves. Muriatic acid fumes are corrosive.
- Keep Pump Running: Ensure the circulation pump is running at high speed to dissipate acid quickly.
- Pour Slowly in Return Stream: Hold the acid container close to the water surface to eliminate splashes. Slowly pour into the deep end flow stream in front of an active return jet.
- Do NOT “Slug” Dose: An old myth recommends pouring acid in one concentrated column on the pool bottom to lower alkalinity. Scientific studies proved this does not selectively drop alkalinity—it simply etches pool plaster at the bottom. Always pour into the return stream.
Frequently Asked Questions
How do I lower high pH in my pool?
To lower pool pH, add Muriatic Acid (31.45% hydrochloric acid) or Dry Acid (Sodium Bisulfate). For example, to lower pH from 7.9 to 7.5 in a 15,000-gallon pool with 100 ppm alkalinity, slowly pour approximately 30 to 36 fl oz of muriatic acid in front of a return jet with the pump running.
Can I use regular baking soda to raise pool alkalinity?
Yes. Pure baking soda is 100% Sodium Bicarbonate, which is chemically identical to expensive pool store "Alkalinity Increaser". Adding 1.4 lbs of baking soda per 10,000 gallons will raise Total Alkalinity by approximately 10 ppm with minimal effect on pH.
What is the difference between Soda Ash and Baking Soda?
Soda Ash (Sodium Carbonate) raises pH significantly and raises Total Alkalinity slightly. Baking Soda (Sodium Bicarbonate) raises Total Alkalinity significantly with only a very mild effect on pH. Use Soda Ash when pH is under 7.2; use Baking Soda when Total Alkalinity is under 80 ppm.
Why does pool pH rise continuously?
pH rise is primarily driven by water aeration (waterfalls, spa spillways, bubbles, splashing) which off-gasses carbon dioxide (CO2). Saltwater pools also experience steady pH rise due to aeration from hydrogen gas bubbles created inside the salt cell.
What happens if pool pH is too low (below 7.2)?
Acidic water (pH < 7.2) is corrosive. It rapidly dissolves copper in pool heat exchangers, etches plaster finishes, degrades vinyl liners, and causes severe eye and skin stinging for swimmers.
What happens if pool pH is too high (above 7.8)?
High pH causes free chlorine to become largely inactive (at pH 8.0, chlorine is only ~20% effective), leading to cloudy water, calcium scale precipitation on tiles and salt cells, and reduced filtration efficiency.