Pool service glossary

Plain definitions for the terms used on the route, with the ranges most techs work to.

Free chlorine (FC)

Chlorine available to sanitize. A common target is 1 to 4 ppm, and with CYA in the water, keep it about 7.5% of CYA or more.

Combined chlorine (CC)

Chlorine that has reacted with contaminants and works poorly. Total chlorine minus free chlorine. The goal is under 0.2 ppm.

Total chlorine

Free and combined chlorine together.

Breakpoint

Raising free chlorine to about 10 times the combined chlorine reading to burn off chloramines.

pH

How acidic or basic the water is. A common range is 7.2 to 7.8, with 7.4 to 7.6 ideal.

Total alkalinity (TA)

The water's buffer against pH swings. Commonly kept at 60 to 120 ppm.

Calcium hardness (CH)

Dissolved calcium. Commonly 200 to 400 ppm for plaster, and 150 to 250 ppm for vinyl and fiberglass.

Cyanuric acid (CYA)

Stabilizer that protects chlorine from sunlight. Commonly 30 to 50 ppm, or 60 to 80 ppm with salt systems. In practice only dilution lowers it.

Saturation index (LSI)

A number that says whether water tends to scale or corrode. Aim for −0.3 to +0.3.

TDS

Total dissolved solids: everything dissolved in the water. It is one of the inputs to the saturation index.

Trichlor

A slow-dissolving, acidic stabilized chlorine, often in tablets. Adds about 6 ppm CYA for every 10 ppm of chlorine.

Dichlor

A fast-dissolving stabilized chlorine granule. Adds about 9 ppm CYA for every 10 ppm of chlorine.

Cal hypo

Calcium hypochlorite, an unstabilized granular chlorine, commonly 65%. Adds calcium.

Liquid chlorine

Sodium hypochlorite solution, commonly 12.5%. Loses strength with heat and age.

Muriatic acid

Hydrochloric acid solution, commonly 31.45%, used to lower pH and alkalinity.

Soda ash

Sodium carbonate, used to raise pH. It also raises alkalinity.

Sodium bicarbonate

Baking soda, used to raise alkalinity with little effect on pH.

Phosphates

A nutrient for algae. Removers treat the reading, while good chlorine levels treat the problem.

SLAM

Short for shock level and maintain: holding a high chlorine level until an algae problem clears.

Salt chlorine generator

A cell that makes chlorine from dissolved salt. Most run at about 2700 to 3400 ppm salt.

Turnover

The time the pump takes to move the pool's whole volume through the filter once.

Prime

A pump is primed when water, not air, fills its basket and suction line.

Route density

How close together your accounts are. Less driving between stops means more stops per day.

Stop

One pool visit on a route day.

Offline-first

Software that saves your work on the device first and syncs when it can, so it keeps working with no signal.