Why the First Month Matters
Fresh plaster is not fully cured when the crew finishes troweling. The cement continues to hydrate and harden over the next 28 days, and the way you treat the water during that time directly affects the final strength and appearance. If the water chemistry drifts out of balance, the plaster can develop a chalky layer called plaster dust, or it can etch and pit. If you skip brushing, the surface can cure unevenly and show trowel marks or dark streaks. The first month is not a suggestion; it is the most important part of the job.
Our crew will fill the pool after the plaster is applied, but the water chemistry at that point is raw. You will need to test the water daily and adjust the pH, alkalinity, and calcium hardness to the levels recommended by the plaster manufacturer. Most manufacturers provide a start-up guide that specifies the target ranges. If you do not have the guide, ask your contractor for a copy. The numbers are different from the levels you would maintain in an established pool, and following them is what prevents the plaster from scaling or staining.
Brushing: The Right Tool and Routine
You need a stiff-bristle nylon brush on a telescoping pole. Do not use a wire brush; it will scratch the new plaster. Brush the entire surface once a day for the first two weeks, then every other day for the next two weeks. The goal is to dislodge the fine cement dust that rises to the surface as the plaster cures. If that dust sits, it hardens into a rough layer that feels like sandpaper and traps dirt. Brushing also helps the surface cure evenly and prevents the formation of a weak, powdery top layer.
Pay special attention to steps, corners, and the waterline tile. These areas tend to collect dust and are harder to reach. Brush in long, overlapping strokes, and rinse the brush often so you are not just moving dust around. The water will look cloudy for the first few days; that is normal. The cloudiness is the plaster dust suspended in the water. Your filter will catch some of it, but brushing is what keeps it from settling. Do not skip a day. Missing even one brushing can let dust harden into a spot that will never match the rest of the surface.
Water Chemistry Targets for New Plaster
For the first 30 days, keep the pH between 7.2 and 7.6, the total alkalinity between 80 and 120 parts per million, and the calcium hardness between 200 and 400 parts per million. The chlorine level should stay low, around 1 to 3 parts per million. Do not use any algaecides, clarifiers, or sequestering agents unless the start-up guide specifically allows them. Some chemicals can interfere with the cure or cause the plaster to discolor. Test the water every day at the same time, and adjust slowly. Large swings in chemistry are harder on new plaster than a steady reading that is slightly off.
If you have a salt chlorine generator, do not turn it on until the plaster has cured for at least 30 days. The high salt concentration can attack the fresh cement and cause pitting or scaling. The same goes for any automatic chemical feeder that adds acid or chlorine directly. For the first month, use manual dosing with liquid chlorine and muriatic acid. It is more work, but it gives you control over the rate of change. After the cure period, you can return to your normal system, but you should still test weekly to keep the chemistry stable.
What to Avoid During the Cure
Do not drain the pool for any reason during the first 30 days. If the plaster is exposed to air, it will dry out too fast and crack. If you need to lower the water level for a repair, wait until the plaster has fully cured. Do not use a vacuum cleaner or a robotic cleaner for the first two weeks. The wheels and brushes can leave marks on the soft plaster. After two weeks, you can use a manual vacuum head with a soft bristle, but avoid anything with hard plastic or metal edges.
Do not let anyone swim in the pool until the plaster has cured for at least 72 hours, and longer if the manufacturer recommends it. The water will be cloudy and the chemicals may irritate skin. Also keep pets out. Their claws can scratch the surface. Do not add any decorative items like fountains, slides, or lights until the cure is complete. The vibration and weight can disturb the plaster while it is still setting. Patience here pays off. A properly cured plaster finish can last 10 to 15 years or more.
Long-Term Habits for a Long-Lasting Finish
After the first 30 days, switch to a weekly testing routine. Keep the pH in the 7.4 to 7.6 range and the calcium hardness above 200 parts per million. Low calcium hardness will leach minerals out of the plaster and make it soft. High alkalinity will cause scaling. Brush the pool once a week to prevent algae and calcium deposits from building up. Use a nylon brush, not a wire brush. Clean the filter regularly so the water stays clear and the pump does not have to work harder than it should.
Watch for early signs of trouble: white spots that do not brush off, rough patches, or a ring of white powder at the waterline. These can indicate a chemical imbalance or a problem with the original application. If you see something that looks wrong, call your contractor and ask them to take a look. Most issues can be corrected if they are caught early. The plaster is a durable surface, but it needs steady care. A little attention each week will keep it looking good and performing well for years.