Low pH is one of the most expensive “quiet problems” in pool care, because it doesn’t just make water feel off, it can actively eat your pool. We sit down with legendary pool chemistry expert Bob Lowry and walk through what aggressive, corrosive water really means in the real world: plaster that starts to etch and turn rough, metal components that dissolve into the water, and the frustrating moment when invisible copper or iron finally hits a saturation point and shows up as stains. If you’ve...

Show Notes

Low pH is one of the most expensive “quiet problems” in pool care, because it doesn’t just make water feel off, it can actively eat your pool. We sit down with legendary pool chemistry expert Bob Lowry and walk through what aggressive, corrosive water really means in the real world: plaster that starts to etch and turn rough, metal components that dissolve into the water, and the frustrating moment when invisible copper or iron finally hits a saturation point and shows up as stains. If you’ve ever wondered why damage seems to appear “all at once,” this explains the chain reaction. 

We also dig into why vinyl liner pools and fiberglass pools can see pH drift lower more often than plaster pools, and why low pH can be harsher on vinyl than high chlorine levels. Then we pivot to spa and hot tub chemistry, where acidic sanitizers like trichlor or dichlor, bather load, and aeration all push pH and total alkalinity in different directions. We tie it back to swimmer comfort, eye and skin irritation, and why combined chlorine (chloramines) becomes noticeable and irritating at surprisingly low levels. 

To close, we lay out practical correction strategies you can use immediately: when borax makes sense, why baking soda is mainly for total alkalinity (and not a true pH fix), when soda ash is the right call because it raises both pH and alkalinity, and how aeration can raise pH after you dial alkalinity in. We also revisit the pH versus chlorine effectiveness debate in the age of cyanuric acid, and why maintaining the right free chlorine level matters more than obsessing over tiny pH swings. Subscribe, share this with a pool owner or tech who’s fighting “mystery stains,” and leave a review with your biggest pH question.

We break down what really happens when pool pH gets too low and why “aggressive” water quietly destroys surfaces, equipment, and even vinyl color. We also share simple, practical rules for testing and correcting pH and alkalinity without guessing.
• low pH making water corrosive and etching plaster
• dissolved metals reaching saturation then showing up as stains
• copper and iron coming from equipment corrosion or fill water
• why vinyl and fiberglass pools drift low without calcium and alkalinity sources
• low pH damaging vinyl faster than many expect
• spa and hot tub factors including acidic sanitizers and bather load
• swimmer comfort range and why chloramines irritate at very low levels
• when to use borax, soda ash, or baking soda based on pH and total alkalinity
• using aeration to raise pH after alkalinity is set
• why cyanuric acid changes the old “pH controls chlorine power” thinking
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