When a swimming pool is freshly plastered, it undergoes a critical curing process that can significantly impact its long-term appearance and durability. Proper start-up procedures are essential to ensure the plaster cures correctly, preventing discoloration, etching, scaling, and other surface issues. By following best practices during the first few weeks, pool professionals can help ensure a smooth, even finish and a longer-lasting pool surface.
Plaster is a cement-based material that continues to cure underwater for at least 28 days. During this time, chemical changes occur that can affect the surface quality. If water chemistry is not carefully managed, issues such as calcium leaching, scale formation, or roughness can develop. The goal of proper start-up practices is to control water chemistry conditions to allow the plaster to cure evenly without damage.
These days, there are at least three popular start-up methods that are employed for newly plastered swimming pools. These startup methods include those recommended by the National Plasterers Council (NPC), onBalance as well as the Calcium start-up technique.
In the NPC startup, the pool water is maintained as balanced (according to NPC recommended water balance parameters) throughout the first 30 days of the plaster curing process.
With the onBalance method, which introduces sodium bicarbonate to the fill water, the idea is to deliver more durable surfaces without the plaster dust.
The Calcium start-up procedure introduces either calcium chloride or sodium bicarbonate to the fill water, focusing on a slightly positive Langelier Saturation Index (LSI) to prevent the loss of calcium hydroxide from the plaster surface as it cures.
Key Start-Up Practices
1. Filling the Pool Properly The first step in the start-up process is filling the pool with water. It is crucial to use a clean, non-metallic hose with the hose end wrapped in cloth and taped. The hose should be placed at the deep end to minimize streaking. The water should not be stopped until the pool is completely full to prevent a waterline mark on the fresh plaster.
2. Balancing Water Chemistry Once the pool is full, water chemistry must be adjusted carefully. The ideal start-up parameters vary by start-up method and include pH, Total Alkalinity, and Calcium Hardness. Cyanuric Acid and chlorine are generally added at some point later in the first 30 days of the startup. A sequestering agent may also be added to help prevent metal staining.
3. Brushing and Filtration Depending on the start-up method employed, new plaster can release fine dust-like particles into the water, which must be removed to maintain a smooth surface. Brushing the pool walls and floor twice daily for the first week helps remove excess plaster dust and prevent calcium deposits. The filtration system should run continuously during this period to aid in clearing the water.
4. Avoiding Chemical Shocks and Aggressive Adjustments Adding too much chlorine too soon or making rapid pH adjustments can cause plaster discoloration and etching. It is best to make gradual changes to water chemistry over the first few weeks.
5. Monitoring and Maintenance Daily water testing is recommended for at least the first week to ensure that pH and alkalinity remain within acceptable ranges. Adjustments should be made carefully to keep water chemistry balanced.
Long-Term Benefits of a Proper Start-Up
It’s important to note that external factors such as rain, wind, and excessive heat or cold can interfere with aesthetic outcomes, so care should be taken to avoid plastering (or use tents or shelters) on days when any of these factors could play a role.
Following proper start-up practices ensures that the pool surface remains smooth, durable, and aesthetically pleasing. Neglecting these steps can lead to costly repairs, discoloration, and premature plaster deterioration. A well-executed start-up not only enhances the pool’s appearance but also extends the lifespan of the plaster, reducing maintenance costs in the long run.
Look for additional articles about plastering best practices in this special issue of Service Industry News. Renowned plaster expert Alan Smith, owner of the Southern Californiabased pool building company Alan Smith Pools, shares his tricks of the trade.
