D'Martinez Academy
Pool maintenance terms glossary
pH, PPM, LSI, chloramines... A quick reference to look up any term without having to search which lesson explained it, with a direct link to the full guide for each one.
B
- Breakpoint
- The chlorine level that must be exceeded in a shock chlorination treatment to fully break down the chloramines that have built up. Read more →
C
- Calcium hardness
- The amount of calcium dissolved in the water. Too low and the water becomes corrosive; too high and it forms limescale deposits. Read more →
- Calcium scale stains
- Whitish limescale deposits on the walls, caused by excess calcium hardness. Treated with a specific acid product. Read more →
- Cell (of the salt chlorinator)
- The component that converts salt dissolved in the water into chlorine, through electrolysis. It has a limited service life. Read more →
- Chloramines (combined chlorine)
- Chlorine that has already reacted with organic matter and is no longer available to disinfect. It's what causes the strong "pool" smell. Read more →
- Cyanobacteria
- The technical name for black algae, they aren't true algae, which is why they resist regular chlorine so well. Read more →
- Cyanuric acid (stabilizer)
- Protects chlorine from sunlight so it doesn't degrade within a few hours. In excess, it makes chlorine lose effectiveness. Read more →
F
- Free chlorine
- The chlorine that's genuinely available to disinfect the water, not combined with anything. Target range: 0.5-2.0 ppm. Read more →
L
- Langelier Saturation Index (LSI)
- A formula that combines pH, temperature, calcium hardness and alkalinity into a single number, to tell whether the water is corrosive, balanced or scale-forming. Read more →
M
- Metal sequestrant
- A product that "traps" metals dissolved in the water (iron, copper...) to stop them from continuing to cause stains. Read more →
- Metal stains
- Reddish, greenish or blackish stains caused by metals dissolved in the water. They don't come out with chlorine, they need a specific sequestrant. Read more →
O
- Over-stabilization
- Excess cyanuric acid in the water, which reduces chlorine's disinfecting capacity even if its level looks correct. Read more →
P
- pH
- Measures whether the water is acidic or basic, on a scale of 0 to 14. Target range: 7.2-7.6. It's the parameter that drags all the others with it. Read more →
- PPM (parts per million)
- The unit used to measure the concentration of chlorine, alkalinity and other parameters already dissolved in the pool's water. Read more →
S
- Salt chlorination
- A system that generates chlorine from salt dissolved in the water, using an electrolytic cell, instead of adding chlorine directly. Read more →
- Sand filter
- The most common filtration system in home pools. The sand compacts over the years and loses effectiveness, which is why it needs replacing. Read more →
- Shock chlorination
- A chlorine dose much higher than the usual maintenance dose, used to fix specific problems such as green water or excess chloramines. Read more →
T
- TDS (total dissolved solids)
- The total amount of salts and minerals dissolved in the water. Usually higher in pools with a salt chlorinator. Read more →
- Total alkalinity
- The water's ability to resist sudden pH swings, without spiking up or down all at once. Target range: 80-150 ppm. Read more →
W
- Winterizing the pool
- Preparing the water and equipment to get through winter unused, avoiding algae, limescale and ice damage. Read more →
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