The five chemistry numbers we check every week (and why)

Most pool problems are chemistry problems caught too late. Algae blooms, cloudy water, eye irritation, equipment damage — they all start with one number drifting that nobody corrected. Here are the five we test on every weekly visit.

1. Chlorine

Free + total chlorine. The sanitizer that keeps the water safe to swim in. In Sarasota, the sun burns it off faster than almost anywhere — it has to be steady or algae moves in. Target free chlorine: 1 to 3 ppm.

2. pH

Acid versus base. The single most-often ignored number on a residential pool, and the one that causes the most damage when it drifts. Wrong pH eats your equipment, irritates eyes, and lets algae grow even when chlorine looks fine. Target: 7.2 to 7.8.

3. Alkalinity

pH’s bodyguard. Alkalinity is what keeps the pH from bouncing all over the place. If alkalinity is low, every dose of acid or base sends pH on a rollercoaster. Target: 80 to 120 ppm.

4. Calcium hardness

Florida tap water is high-calcium. Too much and you get scaling on the tile line. Too little and the water dissolves your plaster. Target: 200 to 400 ppm. Worth watching closely.

5. Salt cell + stabilizer

For salt pools: the cell needs the right ppm to generate chlorine, and the stabilizer (cyanuric acid, CYA) needs to be in range or the chlorine doesn’t hold against the sun. Salt: 2,700 to 3,400 ppm depending on the cell. Stabilizer: 30 to 50 ppm.

Why we adjust on the spot

If something’s off when we test it, we adjust it during the visit — no waiting for a second appointment, no surprise add-ons. Most weeks it’s a small dose of acid or chlorine. Sometimes a shock. Either way, you don’t hear about it. The pool just keeps being swimmable. That’s the quiet part of the job that keeps Sarasota families on the route for over a decade.