A swimming pool is a major investment that adds beauty, relaxation, and value to any property. One of the most critical elements of any in-ground pool is its plaster. Pool plaster not only provides a waterproof seal but also contributes to the pool’s aesthetics and tactile comfort.

Over time, however, plaster can become stained, rough, or damaged if not properly maintained. To ensure your pool plaster remains smooth, clean, and long-lasting, you need a consistent and informed maintenance routine. Here’s how to do just that.

Understand Your Pool Plaster

Before jumping into maintenance, it’s important to understand what pool plaster is. Typically, pool plaster is a mixture of cement, sand, and water that coats the inner walls of concrete or gunite pools. Some plasters may include marble dust or quartz aggregate for durability and visual appeal.

Pool plaster is strong, but it is also porous and susceptible to staining, etching, and roughness due to imbalanced water chemistry or environmental exposure. Knowing your specific plaster type can help you determine the best care routine—white plaster, colored plaster, and aggregate finishes all require slightly different maintenance approaches.

Balance Your Pool Water Chemistry

Perhaps the most crucial factor in preserving smooth, clean plaster is maintaining balanced water chemistry. Poor water chemistry can erode plaster, cause scaling, or result in unsightly staining.

Key Water Parameters:

pH: 7.4 – 7.6

Total Alkalinity: 80 – 120 ppm

Calcium Hardness: 200 – 400 ppm

Chlorine: 1 – 3 ppm

Cyanuric Acid: 30 – 50 ppm (for outdoor pools)

Imbalanced pH or low calcium hardness can cause water to become aggressive, dissolving minerals from the plaster and leaving a rough texture. On the other hand, overly hard water can lead to scale deposits on the plaster.

Use a reliable test kit weekly to check chemical levels and make adjustments as necessary. For large fluctuations or confusing results, consult a pool professional.

Brush Regularly to Prevent Algae and Stains

Routine brushing is vital to maintaining your plaster’s clean and smooth finish. Use a pool brush appropriate for your plaster type—typically, a nylon brush for standard plaster and a stainless-steel brush for tougher surfaces.

Brushing Tips:

Brush your pool 2–3 times per week, especially in areas with less water circulation.

Focus on corners, steps, and behind ladders.

After adding chemicals, brush thoroughly to distribute them evenly and prevent concentration stains.

Brushing prevents algae buildup and reduces the risk of calcium deposits forming, both of which can lead to surface staining or rough patches.

Clean and Vacuum Weekly

Dirt, leaves, and other organic debris can stain plaster if left too long. Weekly vacuuming—whether manual or with an automatic pool cleaner—helps keep the pool floor spotless.

Also, consider:

Skimming daily to remove surface debris.

Emptying skimmer and pump baskets to maintain good circulation.

Removing organic matter quickly prevents tannin stains and inhibits algae growth, keeping your plaster in top condition.

Prevent and Remove Stains

Even with proper maintenance, pool plaster can develop stains from metals, organic materials, or calcium scale. Identifying the type of stain is the first step toward effective removal.

Types of Stains:

Organic stains (leaves, algae): Typically green or brown; remove with brushing and shock treatment.

Metal stains (iron, copper): Appear as rust-colored or blue-green; treat with a metal sequestrant.

Calcium scale: White, crusty buildup; remove with a pumice stone or professional descaling.

To prevent stains:

Use a metal sequestrant regularly if your water has high metal content.

Ensure proper pH and alkalinity levels.

Never leave leaves or debris in the pool for extended periods.

Control Calcium Buildup

Over time, calcium deposits can develop on plaster due to hard water or high pH levels, leading to a rough and unsightly surface.

To control calcium scale:

Keep calcium hardness and pH within ideal ranges.

Use a scale inhibitor as part of your pool chemical routine.

Periodically inspect and clean tile lines and waterline areas where scale often accumulates.

If calcium buildup becomes significant, you may need a professional acid wash or bead blasting to restore the surface.

Consider Periodic Acid Washing

When stains or roughness become too tough to brush away, an acid wash can help restore your plaster’s appearance. This involves draining the Commercial Pool Renovation and applying a dilute muriatic acid solution to remove a thin layer of plaster and surface contaminants.

Caution: Acid washing should only be done every few years and only by experienced individuals. Overuse can thin the plaster prematurely and reduce its lifespan.

Monitor for Cracks or Delamination

Over time, plaster can develop cracks, spalling, or delamination (peeling or flaking), especially if the pool surface is old or water chemistry has been poorly managed.

Inspect the plaster regularly for:

Hairline cracks

Rough or pitted areas

Bubbling or peeling surfaces

Early detection allows for targeted repairs, such as patching or resurfacing sections before the problem spreads.

Replaster When Needed

Even with perfect maintenance, plaster won’t last forever. Most plaster finishes last 7–15 years, depending on material and maintenance. When your plaster becomes permanently rough, discolored, or cracked, it may be time for replastering.

This process involves draining the pool, chipping away the old plaster, and applying a fresh coat. You can also upgrade to a longer-lasting aggregate or quartz finish during this time.

Winterize and Open Properly

In colder climates, proper winterization protects plaster during the off-season. Draining below the skimmer, balancing the water chemistry, and using a winter cover helps avoid freeze damage and staining.

In spring, open the pool carefully:

Remove debris before starting circulation.

Rebalance water gradually.

Avoid shocking the pool with undiluted chemicals.

Taking care during the transition periods extends the life of your plaster and reduces the need for early repairs.

Final Thoughts

Maintaining your pool plaster for a smooth, clean finish isn’t difficult, but it does require consistency and a good understanding of your pool’s needs. With balanced chemistry, regular cleaning, and prompt attention to issues, you can enjoy a pristine swimming experience year after year. Whether your plaster is brand-new or several seasons old, these practices will help you protect your investment and enjoy crystal-clear waters and a beautiful pool surface.