EQUIPMENT
The salt system is showing Low Salt
Do not reach for the salt bag yet — measure the actual level first, because cold water and a scaled-up cell both make the unit read low; the number to hold is 3,000–4,000 ppm.
A salt chlorinator does not measure salt directly. It measures how well the water conducts, then converts that to a salt figure — so anything that reduces the current through the cell, colder water or scale on the plates, shows up as a Low Salt warning even when there is plenty of salt in the pool.
The dose rate is the same on any pool: 1 kg of salt per cubic metre of water raises the level by roughly 1,000 ppm. So a 50 m³ pool reading 2,500 ppm needs about 50 kg to reach 3,500 ppm.
Measure the salt with a test strip or your own meter. Do not go by the unit's own display.
If you have no test kit, bring a bottle of the water to us and we will read it in the lab, free.
If the reading really is below 3,000 ppm, work out the dose from the rate above.
Switch the chlorinator off, but leave the pump running.
Pour the salt into the shallow end. Never tip it into the skimmer — undissolved salt goes straight through the pump and the cell.
Brush the piles on the floor around until they have dissolved.
Run the pump for another 24 hours before you switch the chlorinator back on or re-test.
If the salt is right and the warning stays
Confirm first that the measured salt really is in the 3,000–4,000 ppm band.
Take the cell out and look between the plates. White flaky deposits are scale, and need cleaning off.
Mix the cleaning solution at 1 part acid to 10 parts water, pouring the acid into the water.
Stand only the plate section in it for 10–15 minutes, until the fizzing stops.
Rinse the cell thoroughly with clean water before refitting it.
Two things people get wrong
Salt is not consumed by making chlorine. You only lose it to backwashing, draining and rain overflow — so if you are adding salt unusually often, check for a leak.
Cells produce much less below about 18–20 °C, so on a cool morning the warning can appear on its own and clear by midday.
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