It is an unfortunate fact that most tap water used to fill swimming pools is often soft, aggressive, and somewhat harmful to a new plaster surface. Therefore, in order to not damage a new plaster surface, the tap water needs to be “balanced” before it comes into contact with the new plaster.
That is the purpose of a Bicarb start-up. By “balancing” the tap water before it enters the pool, brand new plaster is protected from being dissolved and losing some cement material from the surface. When plaster material is removed from the surface, it creates roughness and porosity, and consequently, it loses some durability and long-term resistance to wear and tear. A Bicarb start-up generally preserves a very smooth, dense, and durable plaster finish, without any plaster-dust to deal with.
In order to protect and help new plaster cure properly, the CSI of the tap water should be about +0.3 to +0.7 for about 2 to 3 weeks. This can be accomplished by adding sufficient alkalinity (in this case, sodium bicarbonate, also known as baking soda or Bicarb) to the tap water so that the water is not aggressive to new plaster. A minimum of 200 ppm of total alkalinity (TA) is required, but a higher TA amount may be needed based on the calcium content of the tap water.
The equipment needed for this program is a 55 gallon barrel (drum), several water hoses, and some water hose connection fittings. A test kit that has “Acid Demand” capability and a pH meter would be helpful when the pH of the water is above 8.2.
If desired, the following information is a guideline for pool owners to perform a Bicarb start-up. It is applicable to all newly plastered pools, including, colored, quartz, and pebble aggregate finishes. There are no guarantees due to the many variables of swimming pools, quality of plastering, and tap water conditions and resources. But research has shown that this program is beneficial to a new plaster pool. Many pool plastering and pool service firms are using this start-up method and are having good success.
Step 1 – Pre-testing the Fill Water
Test the chemistry of the tap water that will be used to fill the pool. The key parameters to test and record are the pH, TA, Calcium Hardness (CH).
Step 2 – Calculating the Chemical Dose for adding sodium bicarbonate (Bicarb)
Add the Alkalinity and the Hardness numbers together. Then we subtract that number from 500. The result is the amount of sodium bicarbonate in ppm to add. For example, if the fill water Alkalinity is 90 and the fill water CH is 200, then 210 ppm of new bicarbonate needs to be added: 500 – (90 + 200) = 210
Use TFP’s “Pool Calculator” to determine amount of sodium bicarbonate to add to the barrel based on gallonage of the pool.
If the combined levels of the alkalinity and the calcium hardness of the fill water is 500 ppm or higher, and the pH is between 7.2 and 8.2, then no addition of sodium bicarbonate is necessary. Just fill with that water - it is already perfect for new plaster pools.
Step 3 – Setting up the Delivery System
The 55-gallon plastic barrel will need garden hose connections installed, and the specific modifications are as follows:
An 8 to 10 inch hole (or larger) cut in the top of the barrel to facilitate adding the Bicarb.
A female hose connector mounted halfway up the “back” or “deck” side of the barrel for the tap (source) water hose to be attached to.
Three male hose connectors mounted about 4 inches 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 barrel.
A hose is run from the home water faucet to the deck-side fitting, and three hoses are fun from the top pool-side fittings to the bottom of the pool, and the ends of each hose in the bottom of the pool is wrapped in cloth and taped to prevent the cloth from coming off during filling. Bicarb is added to the barrel before the water is turned on.
Step 4 – pH Adjustment
If the pH of the tap or fill water is below 8.3, no adjustment is necessary.
Tap or fill water that is higher than 8.3 is somewhat problematic; however, one can slowly add a pint of acid to the water barrel to lower the pH in the barrel of water. But be careful, there can be a problem due to off-gassing (a lot of bubbles or foaming) of carbon dioxide inside the barrel. If the pool owner is comfortable doing this, then a pint of acid can be added to the barrel after every 4,000 to 5,000 gallons of water is added to the pool.
Step 5 – Determining Fill Delay, Turning On the Water
In consultation with the plasterer or contractor, decide when the water will be turned on after the crew finishes the pool. It is advisable to allow 6 hours between final troweling and turning on the water.
When the water is turned on, the barrel will fill, and will gravity-flow out the top three hoses and into the pool. The Bicarb powder should slowly dissolve as the pool fills.
At the pre-determined time, ensure that the water is turned on and that the flow through the barrel to the pool is working properly, without leaks.
Ensure that the water fills uninterrupted from main drain to surface tile.
Step 6 – Making Adjustments
Once the pool is filled, check the pH, which will probably be at or near 8.3.
Test the Alkalinity, which could be anywhere from 150 to 350 ppm.
If the pH is higher than 8.0 (which is likely), add acid to adjust the pH down to around 7.6 using the “Acid Demand” test.
Step 7 – Monitoring the Progress
Over the course of the following 4 weeks, ensure that the pool is being brushed and filtered per the plasterer’s guidelines, and chemically maintained per TFP guidelines, except for the TA which is to remain higher than normal.
If the Calcium hardness level is below 150 ppm, add calcium chloride as needed, using the Pool Calculator for dosage amount. But be sure the pH is below 8.0 before adding calcium chloride.
For the first month of the Bicarb program, it is better to use Dichlor, or more preferably, Trichlor tabs for sanitizing, instead of liquid bleach or Cal Hypo to help reduce the natural pH rise.
The TA can remain high for one month as long as the pH is maintained below 8.2.
Use the “Acid Demand” test to adjust pH (when it rises to 8.0) downward to around 7.6.
Step 8 – Final Balancing
After 3 to 4 weeks, begin lowering the TA to the proper range as recommended by TFP. Use the Acid Demand test for proper dosages of acid.
As long as the pH remains below 8.2, there should not be plaster dust or scale formation.
A continued brushing regiment is always beneficial and recommended.
If water tanks are brought in by trucks for filling of pool, Bicarb can be added to the tankers for same program and results.
P.S. An important step for a superior plaster finish and water chemistry start-up is to wait at least six hours before turning on the water to fill the pool. If filled too early, some plaster material dissolves from the surface, leaving it slightly porous and more susceptible to further erosion and staining.
Even if the tap water is CSI balanced, it is still aggressive to new plaster and will remove some plaster material from the surface (as evidence by the plaster dust) and negatively affect the long-term durability due to increased porosity of the surface. After the new plaster pool is a month old, maintaining a balanced CSI is recommended from that point forward. Far more damage can occur to a new plaster surface during filling than during the following two weeks, even if not perfectly balanced. And months later, when the plaster surface looks aged, dull, and dirty, no one will suspect it was due to the improper or ineffective fill and start-up program the pool received.
Because the Bicarb start-up preserves a smoother, denser, and more durable plaster surface (without plaster dust), it is easier to remove mineral stains, and stands up better to future acid washes. Dark colored plaster stays darker and does not become blotchy or lighter in color. Long-term aesthetics is improved.
Unfortunately, some pool builders and plasterers give quartz aggregate pool finishes an "acid type treatment" (to supposedly bring out the color) before or after the pool is filled with water. Acid treatments simply makes the surface etched and more porous. An acid treatment can cause increased plaster dust and streaking, and it simply ages the pool. It will not last as long as it could have.
For the past 15 years, many pool plasterers and service techs report having great success with the Bicarb start-up method.
Also might be worth reading: research-reveals-need-for-pool-plastering-standards-t57338.html
Questions may be directed to onBalance at TFP
And Thanks to JasonLion for consultation and suggestions.