Start-ups: Methods to make sure plaster is cured properly
By Marcelle Dibrell
In our last issue, we wrote about spring openings, the procedures that are followed in colder climates to ready a pool for the swimming pool season.
In addition to annual pool openings, the spring months are also among the busiest for new pool construction, refurbishing, and refinishing. While the start-up procedures are usually overseen by the plasterer, it’s not only common but prudent for the service technician to get involved in the process as soon as possible.
New plaster goes through an underwater curing process called hydration that can take up a month to complete. This is a critical time when the pool surfaces are most susceptible to scaling, staining, and discoloration.
Several factors can help to contribute to a less than perfect plaster appearance, and a service pro is well advised to get involved in the process and develop a good working relationship with the plastering company to help avoid unnecessary oversights.
Swimming pool start-up procedures used to break in a newly plastered pool are critical to the long term integrity and appearance of a pool, and some general guidelines should be followed.
Steps should be taken to minimize and remove any plaster dust from settling in the pool-It can re-adhere itself to the surface in the form of scale.
Source water should be tested for metals. If the metals come out of solution, they will easily stain new plaster surfaces and could permanently blemish pool surfaces.
Sequestering agents should be added to source water found to have a high metal concentration.
The pool should be thoroughly inspected for any sign of imperfections. Excess plaster on the deck, steps and railings should be noted. The homeowner should be informed of unprofessional plastering practices that leave permanent marks such as foot prints or trowel marks.
The pool should be filled quickly and without interruption, using multiple hoses when possible. A ring around the pool can form if water flow is stopped during the filling process, and shading problems can occur if the pool is filled too slowly.
The filtration system should be immediately available once the pool is filled. It should be checked for full functionality and cleaned to ensure that dirty water is not entering the brand new pool.
The pool should be regularly and thoroughly brushed to avoid the precipitation of plaster dust from forming scale on surfaces. Brushing also discourages algae from taking root while the pool is un-chlorinated.
Pool owners should be discouraged from using the pool during the start-up procedure to avoid staining the surfaces with body oils. Furthermore, the varying chemical levels can be harmful or irritating to swimmers.
As to the chemical specifics on start-up procedures, there is some debate as to the best practices for new plaster pools. Some experts recommend an acid start-up, some prefer a pH neutral procedure, and some recommend high bicarbonate levels, among others.
The National Plasterers Council, in an effort to standardize the process, has developed start-up procedure guidelines, and these are popularly used on new plaster pools. Their method is based on the use of the Langelier Saturation Index, an industry standard for water balance.
A different theory for start-ups places importance on elevated bicarbonate levels. Recommended by onBalance, this start-up procedure claims to give harder, less porous surfaces that are not as prone to future staining.
In accompanying stories, we will feature the NPC plaster start-up guidelines, as well as the bicarb start-up procedure, endorsed by onBalance.
The Bicarb Start – Pre-treating Fill Water for New Plaster Pools
OnBalance’s Preferred Start up Method
Saturating fill water with baking soda, or sodium bicarbonate, accomplishes two goals. It ensures a pH of 8.3 or lower, which prevents the formation of scale due to plaster dust. It also impedes the dissolution of calcium hydroxide from the plaster surface by converting the surface calcium hydroxide into a protective layer of calcium carbonate, which has a dense and harder surface that is smoother than traditional start-up procedures.
It is an improvement on an acid start-up that reduces plaster dust but does so at the cost of etching the entire pool surface, leaving it more porous, prone to future staining, and more difficult to clean in the long run.
The steps to a bicarb start-up are as follows:
Step 1 – Pre-testing the Water
• Test the chemistry of the tap water that will be used to fill the pool. The key characteristics are pH, Alkalinity, Hardness, Copper and Iron.
Step 2 – Calculating the Chemical Dose
• Add the Alkalinity and the Hardness numbers together. Then subtract that number from 500. The result is the amount of bicarbonate in ppm to add. (For example, if the fill water Alkalinity is 90 and the fill water Hardness is 200, then 210 ppm of new bicarbonate needs to be added: 500 – (90 + 200) = 210)
• Apply the Simplified Dosage Formula for raising alkalinity using sodium bicarbonate: (Volume ÷ 71,425) x ppm to add = pounds to add. (For example, if the pool will hold 20,000 gallons, and it needs 210 ppm of bicarbonate alkalinity: (20,000 ÷ 71,425) x 210 = 58.8, or about 60 pounds to add)
• If the Alkalinity and Calcium Hardness combined equal 500 ppm or higher, then no addition of sodium bicarbonate is necessary – do a traditional start.
Step 3 – Setting up the Delivery System
• Set up a 55-gallon plastic drum that has garden hose connections added to it. The drum should include the following modifications:
Cut an 8 to 10 inch hole in the top of the barrel to facilitate pouring in the bicarb, Mount a female hose connector halfway up the “back” or “deck” side of the barrel, mount three male hose connectors about 4" below the top lip on the “pool” side of the barrel, enough to make sure that sufficient output hoses are provided to handle the pressurized input from the tap without overflowing the drum, and mount one fitting at the bottom of the pool side of the barrel, which leads to a plastic ball valve and then a male hose connector (this is for final draining purposes).
• To start the process, run a hose from the home water source to the deck-side fitting, and run three hoses from the top pool-side fittings to the bottom of the pool, with the ends wrapped in cloth and taped. Add the baking soda (technical grade sodium bicarbonate is fine) to the drum before any water is turned on.
Step 4 – pH Adjustment
• If the pH of the fill (tap) water is over 8.2, add 1 quart of acid to the drum once the drum is full of water.
Step 5 – Determining Fill Delay, Turning On the Water
• In consultation with the plasterer, decide when the water will be turned on relative to the crew finishing the pool. Conditions permitting, encourage the plasterer
to allow at least 6 hours between final troweling and turning on the water.
• Turn the water on, which fills the barrel, and gravity-flows out the three top hoses into the pool. The powder will slowly dissolve as the pool fills. Make sure that the flow through the barrel to the pool is working properly, without leaks. Working with the homeowner, ensure that the water fills uninterrupted from main drain to surface tile. When the pool is full, drain the barrel through the bottom pool-side drain fitting into the pool, and rinse any remaining powder into the pool.
Step 6 – Making Adjustments
• Once the pool is filled, double check the pH, which should be right at 8.3. This requires the use of a pH meter, since 8.3 is at the extreme high detection range
of phenol red.
• Double check the Alkalinity, which should be anywhere from 100 to 350 ppm.
• If the pH is 8.2 or higher, add acid to adjust the pH down to the high 7 range – 7.7 to 7.9ish.
• If the Hardness level is below 150 ppm, add calcium chloride as needed, using the Simplified Dosage Formula for adding Hardness (see reverse). Be sure the pH is below 8.2 before adding calcium chloride.
• Recheck the copper and iron levels and add chelating agents as needed.
Step 7 – Monitoring the Progress
• Brush and filter the pool daily for the first two weeks, and chemically maintain per APSP standards.
• Add cyanuric acid, borax, chlorine, etc. according to your normal practice to reach to target maintenance levels. Always pre-dissolve powders before adding.
• For the first month after fill, allow the alkalinity to remain as high as it was from the start-up, and ensure that the pH remains at 8.2 or lower.
• For the first month use an acidic sanitizer so the pH remains below 8.3.
Step 8 – Final Balancing
• After a month, begin adding acid until the Alkalinity reaches the target range.
• There is no great hurry to finish that – as long as the pH remains below 8.3, there will be no plaster dust and no scale formation.
National Plasterers Swimming Pool Start-Up Procedures
The pool finish will start to hydrate immediately after mixing, with the majority of hydration taking place within the first 28 days. This critical time period is when a finish is most susceptible to staining, scaling and discoloration. Proper start-up procedures including timely brushing and constant monitoring and adjusting of the pool water is mandatory. The following recommended start-up method is based on procedures shown to produce the best aesthetic results. Due to unique local water conditions and environmental factors, parts of these recommended start-up procedures may need to be modified to protect the pool finish. For example: filling the pool with extremely low calcium hardness, low pH or low total alkalinity levels may necessitate changes to these procedures. Brushing and monitored chemical adjustments will be mandatory by the homeowner or a trained pool technician during the service life of any pool surface.
ALWAYS ADD A CHEMICAL TO WATER, NEVER WATER TO THE CHEMICAL.
POOL FILLING DAY
Step 1. Make sure the filtration equipment is operational.
Step 2. Remove all floor return heads and directional eyeballs (if appropriate and recommended in your geographical area).
Step 3. Based on temperature and type of finish, fill the pool to the middle of the skimmer or specified water level without interruption as rapidly as possible with clean potable water to help prevent a bowl ring. Place a clean rag on the end of the hose, always placed in the deepest area, to prevent damage to the surface material. If a water truck is required, 24 inches (60 cm) of water should be placed at the deepest area for a water cushion. Wheeled devices should not be used in the pool until after 28 days.
Step 4. At no time should any person or pets be allowed in the pool during the fill. Do not allow any external sources of water to enter the pool to help prevent streaking. It is recommended that you do not swim in the pool until the water is properly balanced.
Step 5. Test fill water for pH, alkalinity, calcium hardness and metals. Record test results.
Step 6. Start the filtration system immediately when the pool is full to the middle of the skimmer or specified water level.
1st DAY (It’s vital to follow these steps in order - prior to proceeding to the next step)
Step 1. Test pH, alkalinity, calcium hardness and metals. Record test results.
Step 2. High alkalinity should be adjusted to 80 ppm using pre-diluted Muriatic Acid (31-33% Hydrochloric acid). Always pre-dilute the acid by adding it to a five gallon (19 L) bucket of pool water
Step 3. Low alkalinity should be adjusted to 80 ppm using sodium bicarbonate (baking soda)
Step 4. pH should be reduced to 7.2 to 7.6 adding pre-diluted Muriatic Acid if the alkalinity is already 80-100 ppm
Step 5. Brush the entire pool surface thoroughly at least twice daily to remove all plaster dust.
Step 6. Although optional, it is highly recommended to pre-dilute and add a quality sequestering agent using the recommended initial start-up dosage and then the recommended maintenance dosage per the sequestering agent’s manufacturer.
Step 7. Operate filtration system continuously for a minimum of 72 hours.
Step 8. DO NOT add chlorine for 48 hours. DO NOT turn on pool heater until there is no plaster dust in the pool.
2nd DAY - Brush the Pool
Step 1. Test pH, Alkalinity and Calcium Hardness and repeat steps of 1st Day except for Step 6.
Step 2. Once the alkalinity is adjusted to 80ppm and the pH is adjusted to 7.2 to 7.6, then adjust calcium hardness levels to a minimum of 150 ppm.
(Caution: Adjustments requiring more than 20 lbs. of CaCl2 should be pre-diluted and added in 10 lbs. increments - morning and afternoon)
Step 1. Test pH, Alkalinity and Calcium Hardness and repeat 1st Day Steps 1 through 6.
Step 2. Pre-diluted chlorine may now be added to achieve 1.5 to 3 ppm. NO SALT SHOULD BE ADDED FOR 28 DAYS.
Step 3. Brush the entire pool surface thoroughly at least twice daily to remove all plaster dust.
4th THROUGH THE 28th DAY
Step 1. Test pH, Carbonate Alkalinity and Calcium Hardness and repeat 1st Day Steps 1 through 5 every day for 14 days to help prevent the scaling of the pool surface.
Step 2. On the 7th day, if there is any plaster dust remaining - remove it using a brush pool vacuum.
Step 3. After the 4th Day — calcium levels should be adjusted slowly over the 28 day period not to exceed 200 ppm.
Step 4. After the 4th Day — adjust Cyanuric acid levels to 30 to 50 ppm based on the primary sanitizer of the pool (pre-dissolve and add through the skimmer).