What to tell your pool tech before a visit

This guide from Sullivan's Pool Service summarizes the cited guidance. Before a pool tech arrives, it helps to know your water's recent numbers. Test chlorine and pH at least twice per day with a DPD test kit, and note the total chlorine, free chlorine, and combined chlorine readings, since combined chlorine equals total chlorine minus free chlorine. Mention any chloramine odor, eye or skin irritation, or poop in the water, and share the pH and free chlorine results so the visit starts from accurate information.

By Ryan Sullivan · Published October 8, 2026

Drafted with AI assistance from its cited sources and checked automatically before publication: every figure must appear in those sources. How our guidance is prepared.

Your own readings give the visit a starting point

Testing chlorine and pH on a regular basis is part of owning a residential pool or hot tub. The readings you take help protect the people who use the water from swimming-related illnesses, so keeping up with them matters even between service visits.

Chlorine gets used up by ordinary things. Sweat, pee, poop, and dirt that swimmers carry into the water all lower the concentration, and so does sunlight. In a hot tub, the jets can lift water into droplets and mists, which also brings the chlorine level down. That is why the chlorine concentration needs routine checking rather than an occasional glance.

At least twice a day is the testing rhythm for both chlorine and pH, and if a number of people are using the pool or hot tub, test more often than that. When your readings are current, a technician visit starts from what you already know.

Use a DPD test kit for numbers you can pass along

When the goal is readings worth passing along, the type of test kit matters. A DPD test kit, short for N,N Diethyl-1,4 Phenylenediamine Sulfate, gives the most accurate chlorine and pH results for pools and hot tubs. Test strips are convenient, but they are less accurate than a DPD kit, so readings taken with strips are a weaker starting point for a visit.

There is one known limitation to keep in mind with DPD testing. If the water sample has a chlorine concentration above 10 ppm, the test can partially or totally bleach out, which shows up as a falsely low reading or even 0 ppm chlorine. If a sample turns clear or the result seems impossibly low, that bleaching effect is a possibility worth mentioning when the numbers get passed along.

Whichever kit ends up in hand, the manufacturer's directions are the guide. Following them is what makes the readings reliable enough to share.

Give both chlorine numbers, not just one

Chlorine comes in more than one form, and a single number hides the difference. Total chlorine counts everything in the water, while free chlorine counts only the portion still able to sanitize. Reporting both gives a far clearer picture than reporting either one alone, because the gap between them is where the useful information sits.

That gap is combined chlorine, found by subtracting the free chlorine reading from the total chlorine reading. Combined chlorine includes chloramines, which form in the water and then move into the air just above the surface. They are the compounds most often blamed for the smell people associate with a heavily used pool.

Most local health departments set a limit for combined chlorine in the water at 0.4 ppm or less. Passing along both chlorine readings lets your tech check where the water stands against that figure before deciding what to adjust.

pH readings mean more than you might expect

pH is one of those numbers that seems like a side note next to chlorine, but it changes what the chlorine reading actually means. The CDC recommends keeping pool water between a pH of 7.0 and 7.8, with a chlorine concentration of at least 1 ppm in pools and at least 3 ppm in hot tubs. If the water is treated with cyanuric acid, a stabilizer found in products commonly sold as dichlor or trichlor, the CDC sets the pool chlorine minimum at 2 ppm instead, with the same pH range.

The reason pH matters so much is that it governs how well chlorine can do its job. As pH rises, chlorine's ability to kill germs falls, and the effect becomes especially pronounced above 8.0. A chlorine reading that looks fine on paper can be less effective than it appears.

Low pH has its own tradeoffs. Below 7.0, chlorine kills germs more effectively, but the water becomes harder on pipes, which are more likely to corrode or break down in that range.

What the numbers explain about symptoms

Symptoms around a pool often trace back to the water chemistry itself. Chloramines, which form in treated water, can irritate the skin, the eyes, and the respiratory tract, including the nose. This happens when chloramines escape the water and become gas in the air above it, and the effect is particularly noticeable indoors, where that air has less room to disperse.

Knowing what to watch for helps you describe the problem accurately. Be alert for poop in the water, for a distinctive chloramine odor in the swimming area, and for irritation of the respiratory tract, eyes, or skin in swimmers and staff who spend time in that area. Noticing any of these gives the visit a concrete symptom to investigate.

Chlorine is added to water to kill germs, but it does not work immediately. Used properly, it can kill most germs within a few minutes. One corrective rule worth knowing: raise the free chlorine level to 10 times the combined chlorine level.

Next step: weekly pool cleaning service.

Sources

Where Sullivan’s works

Sullivan’s Pool Service maintains pools in and around Austin, including Northwest Hills, South Austin, West Lake Hills, Tarrytown, Great Hills, River Place, Crestview, East Austin, North Austin, West Campus, Hyde Park, Downtown Austin and St. Johns, and in Bee Cave, Cedar Park, Georgetown, Leander, Pflugerville and Round Rock. See every service area.

Weekly residential service has one fixed monthly price, set by pool size: see pool service pricing for what each size tier covers.