Above-ground pool maintenance: the complete guide

The three pillars of clear water

All pool maintenance rests on three actions that complement each other and never substitute for one another. Filtration removes suspended particles. Chemical balance makes the water neither aggressive nor scale-forming, and above all lets the disinfectant do its work. Disinfection eliminates bacteria and algae.

The most common mistake is trying to fix cloudy water with chlorine when filtration is running too little or the pH is out of range. In that case the chlorine is consumed with no effect and the problem returns the next day. Always treat in order: filtration, then balance, then disinfection.

• Filtration: removes the physical (dust, pollen, insects)
• Balance: determines how effective everything else is
• Disinfection: eliminates the living (bacteria, algae)

How long should you filter each day?

The reference rule is simple: divide the water temperature by two and you have the number of hours of daily filtration. Water at 26 °C therefore needs about 13 hours. At 20 °C, 10 hours is enough. In a heatwave, at 30 °C, aim for 15.

Run the pump during the hottest hours, when algae photosynthesis is at its most active and bathing is heaviest. Filtering at night to benefit from a cheaper electricity tariff is a false economy: water degrades during the day.

Long continuous filtration beats several short cycles. Every restart gives particles time to settle back to the bottom.

• Water at 20 °C: around 10 h per day
• Water at 26 °C: around 13 h per day
• Water at 30 °C: 15 h, or continuous filtration
• Always during daylight hours by preference

Balance before you disinfect

pH measures the acidity of the water. It should stay between 7.0 and 7.4. Above 7.6, chlorine loses much of its disinfecting power: you can add twice as much with no result. Below 7.0, the water becomes aggressive to skin, eyes and the liner.

Total alkalinity, or TA, stabilises pH. Aim for 80 to 120 mg/L. Alkalinity that is too low produces a pH that wanders from one day to the next and makes any adjustment impossible. It is often the hidden cause of water you cannot seem to stabilise.

Test at least once a week, and systematically after heavy rain, a busy swim or a significant top-up. Test strips are adequate for family use.

• Target pH: 7.0 to 7.4
• Target alkalinity: 80 to 120 mg/L
• Correct alkalinity before pH, and pH before chlorine
• Test after every rainfall or top-up

Chlorine, bromine or active oxygen?

Chlorine remains the most common and least expensive treatment. Effective and residual, it copes poorly with high temperatures and breaks down quickly in sunlight, hence the value of a stabiliser. Its characteristic smell, incidentally, is not that of pure chlorine but of chloramines, a sign that you need to aerate and treat rather than add more.

Bromine is more stable at high temperature and far less irritating, which makes it worth considering if children swim often. It costs more and acts more slowly.

Active oxygen is the gentlest on skin and odourless, but it has little residual action and suits small volumes or a supporting role. For a family above-ground pool, slow-release chlorine tablets remain the best balance of effectiveness and cost.

• Chlorine: economical, effective, needs stabilising in sunlight
• Bromine: stable in warm water, low irritation, more expensive
• Active oxygen: very gentle, little residual action, small volumes

Mechanical cleaning, not to be neglected

No amount of filtration makes up for a dirty floor. A surface net passed every day removes leaves and insects before they sink and decompose, which saves disinfectant.

Brush the walls once a week, paying particular attention to the waterline where a greasy film settles, and to the corners where water circulates poorly. That is where algae take hold first.

For the floor, a manual vacuum connected to the skimmer is enough on small pools. On a tubular pool of three metres or more, an autonomous cleaner saves a considerable amount of time.

The weekly routine in fifteen minutes

Maintenance becomes easy once it is a ritual. A well-drilled weekly sequence takes a quarter of an hour and avoids almost every unpleasant surprise.

• 1. Net the debris from the surface
• 2. Brush the walls, the waterline and the corners
• 3. Vacuum the floor if needed
• 4. Test pH and alkalinity, correct if necessary
• 5. Refill the chlorine or bromine dispenser
• 6. Rinse or clean the filter cartridge
• 7. Check the water level, at mid-height of the skimmer

Green, cloudy or irritating water: the diagnosis

Green water means algae, and therefore a lack of disinfectant, insufficient filtration or a pH that is too high. The course of action: correct the pH, carry out a shock treatment, brush the walls vigorously, then filter continuously for twenty-four to forty-eight hours.

Water that is cloudy but not green most often comes from a clogged filter or an alkalinity imbalance. Clean the cartridge before anything else, it is the cause in the majority of cases.

Water that stings the eyes does not mean too much chlorine, contrary to intuition. It is almost always a pH out of range or a build-up of chloramines. Adding chlorine will not help: you need a shock treatment to destroy the chloramines, then to readjust the pH.

• Green: algae, shock treatment then continuous filtration
• Cloudy: clean the cartridge, check alkalinity
• Irritating: pH out of range or chloramines, not excess chlorine

Maintaining and replacing the cartridge

On an above-ground pool, cartridge filtration is the norm. Rinse the cartridge with a hose every week, spreading the pleats where impurities accumulate. An overnight soak in a degreasing product restores some of its capacity once a month.

A cartridge cannot be rinsed indefinitely. Allow a replacement every four to six weeks in peak season, more often if the pool is heavily used or surrounded by vegetation. A tired cartridge lets fine particles through and produces that milky water nothing seems to fix.

Keeping a spare cartridge avoids running the filtration empty while an order arrives.

Winterising and storage

A tubular pool does not overwinter full in our climates: frost distorts the uprights and cracks the liner. At the end of the season, empty the pool completely, respecting local rules on discharging treated water.

Let the liner dry completely before folding it, since even residual moisture is enough to create mould and stubborn odours. Clean it beforehand with a gentle product, free of solvents.

Store the liner folded without sharp creases, in a frost-free space away from rodents, which readily attack PVC. Put away the pump and hoses emptied of all water, and keep the manual with the equipment: the cartridge references are in it.

• Empty before the first frosts
• Dry completely before folding
• Frost-free space, away from rodents
• Drain the pump and hoses

Safety: what the regulations say

The legal requirement for an approved safety device, introduced by French law of 3 January 2003, applies to in-ground and partially in-ground pools for private use. Demountable above-ground pools are not covered.

That absence of obligation clearly does not remove the need for vigilance. Active, uninterrupted supervision by a designated adult remains the only genuinely effective protection around young children. Removing the ladder after every swim is a simple and remarkably effective habit.

Frequently asked questions