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Pool Owner’s Guide · Your Water
Chlorine: The Quiet Work Behind Clear Water
by Spectrum Pool Care
Chlorine is the reason pool water stays clear, fresh and inviting day after day. Here’s what it does, the level to aim for, and what changes how much your pool needs.
Every day, a pool collects things you can’t see: pollen and dust on the breeze, sunscreen and sweat from swimmers, and the tiny spores that would grow into algae if given the chance. Chlorine works through all of it quietly, breaking down organic matter and keeping algae and bacteria from ever getting a foothold. When it’s at the right level, you simply notice that the water looks clear and feels fresh.
Pool test kits measure chlorine in parts per million (ppm). For most residential pools, the target is 1 – 3 ppm of free chlorine.
Reading the Test
Free, Combined and Total Chlorine
Free chlorine
The chlorine that’s still available to do its job. This is the number that matters most, and the one the 1 – 3 ppm target refers to.
Combined chlorine
Chlorine that has already teamed up with contaminants and is mostly spent. These compounds, called chloramines, cause the familiar “chlorine smell.”
Total chlorine
Free and combined added together. When total reads well above free, the water is asking for a boost to clear out the combined chlorine.
That pool smell
A strong “chlorine” smell usually means combined chlorine is building up, not too much chlorine. Fresh, balanced water smells of very little at all.
What Changes It
Why Some Days Need More
Sunlight. The sun’s ultraviolet light breaks chlorine down quickly. Without stabilizer, a bright afternoon can use up much of it within a few hours.
Heat. Warm water grows algae and bacteria faster, so chlorine has more work to do through a Valley summer.
Swimmers and visitors. A busy weekend or a pool party brings sunscreen, lotion and sweat that use up chlorine.
Wind and rain. Leaves, dust and pollen all draw on the chlorine in the water.
Stabilizer (CYA). Stabilizer protects chlorine from the sun, but it also makes chlorine work a little more gently. The more stabilizer in the water, the more free chlorine the pool needs to stay at its best.
pH. Chlorine works most effectively when pH is in its ideal range of 7.4 – 7.6.
Where It Comes From
Ways Chlorine Reaches the Water
Liquid chlorine
Sodium hypochlorite, the most common choice on service routes. It adds chlorine without adding stabilizer or calcium, which keeps the rest of the water in balance.
Tablets
Slow-dissolving tablets in a feeder or floater are convenient, and they add stabilizer as they dissolve, so stabilizer levels are worth watching over a season.
Granular shock
Used for a larger, one-time boost, for example after a party or a storm. Some types also add calcium to the water.
Salt systems
A salt cell makes chlorine from dissolved salt as water flows through it. The water still holds ordinary chlorine; the cell simply produces it on site.
From our routes: on weekly service we test free and combined chlorine on every visit and adjust for the season, so the level stays steady through heat waves, windy weeks and busy weekends.
