Pool Chemical Balancing Explained
Pool chemistry sounds complicated because the numbers are interdependent, not because any single reading is hard to understand. This site is dedicated to a single build method: gunite (shotcrete) construction, rebar cage, sprayed and hand-finished concrete, engineered bond beams, and a design that can be shaped to anything the lot allows, from tanning ledges to negative edges to integrated spas.
The Four Numbers That Matter
Free chlorine (or bromine) is the sanitizer killing bacteria and algae; pH measures how acidic or basic the water is; total alkalinity is a buffer that keeps pH from swinging; and calcium hardness measures dissolved minerals that affect plaster and equipment.
Of the four, pH and alkalinity move together. Alkalinity below about 80 ppm lets pH bounce around with every rain event or chemical addition; alkalinity above about 120 ppm makes pH stubborn and hard to correct. Fix alkalinity first, then dial in pH.
A Practical Order of Operations
Test alkalinity and pH before adding sanitizer. If alkalinity is out of the 80-120 ppm range, correct it with the appropriate increaser or decreaser and retest the next day before touching pH.
Once alkalinity is stable, adjust pH into the 7.2-7.6 range. Only then does chlorine work as efficiently as it should; chlorine added to water with the wrong pH is partially wasted, which is a common reason a pool "won't hold chlorine" even with frequent dosing.
FAQs
How often should I test pool water?
Twice a week is a reasonable baseline for most residential pools in the Houston area given the long swim season, more often during heavy use (parties, frequent rain) or right after shocking.
Why does my chlorine reading keep dropping overnight?
UV exposure burns off unstabilized chlorine, and heat accelerates the process; a cyanuric acid (stabilizer) level in the 30-50 ppm range protects chlorine from sun loss without over-stabilizing the water.
Where This Fits
See our Pool Repair service page, or Financing if cost is the next question.
Related Reading
Chlorine vs. Saltwater Pools: What's Actually Different
Saltwater pools still use chlorine, generated on-site; here is what actually changes in day-to-day maintenance.
pH and Alkalinity Basics for Pool Owners
Why alkalinity is the buffer behind pH, and how to adjust each one without chasing the other in circles.
Phosphates and Algae Food, Explained
Why phosphate levels matter even when chlorine and pH both test fine.
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