Chemical terminology glossary
BST
Abbreviation for Pool Super Tablet, which contains mainly chlorine, algaecide, and flocculant.
Total chlorine
The sum of free chlorine and combined chlorine present in the water.
Floccer
A flocculant, a chemical used to bind fine impurities in the water — particles smaller than the filter’s capability — into larger flocs that can then be captured by a sand filter.
Chloramines
Compounds formed as a result of chlorine reactions in the water.
ORP (Redox)
An abbreviation for Oxidation-Reduction Potential.
This value indicates the oxidizing and disinfecting capacity of the water and reflects the remaining oxygen level.
ORP is affected by any oxidizing agent added to the water (e.g., chlorine, bromine, or air).
It serves as a key indicator of the bacteriological quality of the water.
According to the World Health Organization (WHO), the ideal ORP value for drinking water is 650 mV, which ensures effective prevention against microbes and bacteria.
pH
The negative logarithm of the hydrogen ion (H⁺) concentration in a liquid — in this case, pool water.
If the concentration of hydrogen ions is higher than that of hydroxide ions (OH⁻), the water is acidic; if lower, it is alkaline.
The correct pH level is essential for water balance.
The ideal pH value for a standard pool is between 6.9 and 7.4, depending on pool coverage and water quality.
The pH of seawater is typically 8.0–8.5, while mountain spring water is around 7.0.
TDS (Total Dissolved Solids)
Represents the total amount of dissolved substances in the water — minerals, salts, calcium, organic and inorganic matter, and other particles such as sulfates, silicates, or residues from urine, deodorants, perfumes, and sunscreens.
High TDS values are caused by the accumulation of these dissolved compounds.
The ideal TDS value should not exceed 900 ppm (parts per million).
Water exceeding this level often smells unpleasant and changes color.
The only way to reduce TDS is to replace a significant portion of the pool water.
Combined chlorine
Chlorine that has already reacted with impurities in the water.
It causes the characteristic “chlorine smell”.
The most common form of combined chlorine is chloramines.
Free chlorine
The active chlorine present in the water, responsible for disinfection.
It reacts with organic impurities to form combined chlorine