France lockdown boosts salt water swimming pools popularity

Why have salt water swimming pools become increasingly popular in France over the past decade?

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Much of the popularity comes from the sensation of being in “softer” water while swimming, with less of the chlorine taste and smell associated with swimming pools – which can lead to itchy eyes, dry skin, allergies, colour changes in costumes, and, in some cases, green hair.

For an initial investment in an electrolyser, pool-owners spend less over the year on chemicals and do not need to add chlorine every week to sterilise the water. They will have to be prepared to replace electrodes in the machine every two or three years, meaning overall running costs can work out about the same, depending on the cost of the electrodes in the system. Stocking and handling of potentially dangerous chemicals are reduced.

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Alexander Pearson, who runs pool building business Gaius Terra & Aqua, near Biarritz, said: “In practical terms, it is a housing which is plumbed into the pool system in line with the filter, which has a control panel on it. The way it works is that the salt water – less salty than sea water –passes through the unit when the pool filter runs, and some of the sodium chloride salt is converted by electrolysis into chlorine, which sterilises the water. Because it is in a form which is directly used by the water, less
chlorine overall is needed, which is why people notice the difference.”

The chlorine, in the form of sodium hypochlorite, is converted back into salt through the action of sunlight, meaning that salt levels in the pool should remain steady. Mr Pearson said there is a large selection of electrolysers in the French market, with prices for installed units usually between €1,000 and €3,000.

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“You should do weekly checks of the level of alkalinity and the PH levels to make sure that they are 7.3 to 7.4 but you do not need to add chlorine.” Salt added to the pool needs to be highly refined. Table salt should not be used, nor should pool salts with added chemicals such as flocculants – if you need to add them for whatever reason, do so manually. Dosage should be from 2.5kg to 5kg/m3 of water – roughly a 10th as salty as sea water.

Various functions, such as alerts when levels of salt fall outside recommended limits, or systems which automatically reduce the amount of chlorine produced when the pool cover is on, are usually found on more expensive models. Typical bills for pool chemicals that are not needed with an electrolyser are around €300 a year. However, the electrodes do need to be replaced, costing €500 on average.

Mr Pearson said that after swimming in a salt pool, people may feel their skin is a bit sticky from the salt, similar to swimming in the sea. “If it is something which bothers you, it is a good idea to have a fresh water shower installed,” he said. Most existing pools can be converted to salt water operation as long as there is space for the unit in the pool house, or they can be installed when the pool is built. Mr Pearson said interest in pools had risen since lockdown. “I have been contacted by a number of people who say they decided to invest in a pool after being frustrated by the restrictions,” he said.