Four-Season Pool Care: The Secrets to Crystal-Clear Water

Run the filtration for at least 8-10 hours a day, apply shock chlorination once a week and check the water level regularly against evaporation.

A weekly water test is the easiest way to catch small deviations before they turn into large problems. Cleaning the skimmer and the floor vacuum regularly keeps the water clear throughout the day.

Lower the water level below the skimmer mouth and drain the lines to prevent frost damage.

A tightly woven winter cover keeps leaves and dirt out of the water and makes the spring opening much easier. If the closing has been done properly, opening in spring is quick. If you would rather not plan this calendar yourself, a seasonal maintenance plan can be drawn up as part of pool consultancy.

Once a week, on the same day and at the same time, follow this order: measure pH and free chlorine with test strips or a drop test, empty the skimmer basket and the pump pre-filter, check that the water level is at the middle of the skimmer mouth, and run the floor vacuum or the robot.

Note the readings on your phone. Two or three weeks of records show the character of the pool: in which weather chlorine consumption speeds up, in which direction pH drifts. If you spot a deviation early, the correction takes a few hundred grams of chemicals; if you spot it late, you end up dealing with shock chlorination and cloudy water.

So if the water smells of chlorine and you are still fighting algae, the problem is usually not chlorine but pH.

Total alkalinity (80-120 ppm) is the buffer for pH; if it is low, pH swings within a day, and if it is high, bringing pH down becomes difficult. When calcium hardness (200-400 ppm) stays low, the water draws the mineral it needs out of the grout and render; when it stays high, it leaves scale on the heater element and on the finish. Read the four values together; correcting one value and upsetting the others is the most common mistake.

The regulation binds primarily pools open to the public, such as those at hotels, residential complexes and sports facilities; it is not mandatory for a private villa pool, but the same values remain the safest target for home use as well. According to its annex table, pH is kept between 6.5 and 7.8; free chlorine ranges from 1 to 3 mg/L in outdoor pools and 1 to 1.5 mg/L in indoor pools; combined chlorine must not exceed 0.2 mg/L.

For pools open to the public, these values must be measured and recorded at least twice a day, and microbiological analyses must be carried out at regular intervals by an authorized laboratory. Responsibility for measurement and record-keeping rests with the pool water operator; certification and training requirements are the subject of a separate article. When a four-season pool maintenance plan targets the regulation's values, a weekly checklist takes shape on its own: pH and chlorine every day, alkalinity once a week, calcium hardness and cyanuric acid once a month.

Note the operating pressure with a clean filter; when the gauge rises 0.3-0.5 bar above it, it is time to backwash. Continue backwashing until the water runs clear (usually 2-3 minutes), then rinse for 30-40 seconds and return the valve to filtration.

Filter sand is renewed every 5-7 years; when the grains become rounded and lose their holding capacity, backwashing becomes more frequent and the water never quite sparkles. When replacing, glass media can also be considered: it holds finer particles, uses less backwash water and lasts about twice as long as sand.

Because the water stays warm, chlorine consumption continues; filtration time is not reduced below 6 hours a day.

In indoor pools, the second half of the work is in the air: when humidity rises above 60 percent, condensation starts corrosion on the glazing, the ceiling and the metal fittings. Check the filters of the dehumidification unit once a month. In an outdoor pool, an automatic cover cuts evaporation loss and heat loss in winter; an outdoor pool heated without a cover pays for its energy to the sky.

The second is starting the season without backwashing the filter; sand that has rested over winter returns what it has held to the water at the first start-up. The third is adding chemicals all at once and without running the pump; without circulation, chemicals settle on the floor and stain the finish.

The fourth is pouring algaecide straight into green water: shock chlorination and brushing come first, as algaecide can only do its protective job in clean water. The fifth is dosing without measuring; every chemical added by eye produces a new deviation to be corrected the following week. An hour of measurement and step-by-step work at opening is the insurance against rescue operations that would last for days in July.