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Thread: The Bicarb Start-up and Why it Works

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    The Bicarb Start-up and Why it Works

    The following information on Bicarb start-ups is applicable to all newly plastered swimming pools, including color, quartz, and pebble aggregate finishes.

    The first step for a superior start-up is to wait at least six hours (after the plastering is completed) before turning on the water to fill the pool. This was common practice in the old days. If filled too early, some plaster material dissolves from the surface, mainly in the deep end, leaving it porous and susceptible to further erosion and staining.

    The second step is to fill the pool with water that has sufficient calcium, or more importantly, a high alkalinity (TA) level. The best water for new plaster should have a positive Langelier Saturation Index (LSI or CSI). Even if the tap water is balanced, it is aggressive to new fresh plaster and will remove material from the surface and negatively affect the long-term durability due to increased porosity of the surface.

    Those first two steps are, for the most part, what the Bicarb Start-up program is all about. It is not any more complicated than that. Other start-up procedures, such as the Traditional start-up, do not deal with these two important steps, which may allow filling the pool too soon, and with aggressive tap water. Only afterwards when the pool is full, when the damage has already occurred, is the water treated and balanced. Far more damage can occur to a new plaster surface during filling than over the following two weeks, even if not balanced.

    When water and pool cement is mixed together before applying, most of the hardening plaster is comprised of calcium silicates and aluminates, and about 15 to 20 percent is calcium hydroxide. Calcium silicates and aluminates are the hardest components, but calcium hydroxide is softer, slightly soluble, and a weaker component of pool plaster. In fact, calcium hydroxide can be dissolved by typical balanced pool water. The LSI (or CSI) is applicable to calcium carbonate, not calcium hydroxide.

    This is exactly why tap water that does not have a positive LSI is not suited for new fresh pool plaster. As much as 30 pounds of calcium hydroxide and other pool plaster material can be dissolved from the plaster surface of a 20,000 gallon pool, depending on the severity of the plastering and aggressive tap water conditions. The calcium hardness of the pool water can sometimes increase 100 to 200 ppm.

    It is the dissolved calcium hydroxide that becomes plaster dust¯ (in the pool), as much of it is transformed into insoluble calcium carbonate by the pool water. The amount of plaster dust formed can indicate how much material has been lost from the pool plaster surface. The more material that is lost, the more porous and rougher the plaster surface is (as seen under magnification), the less durable it is, and the more likely dirt, iron, and copper will stick to the surface as time passes. And months later, when the plaster surface looks dirty and stained (gray mottling is a different issue), no one will suspect it was due to the improper or ineffective start-up program the pool received. Whoever is maintaining the pool will be blamed for the negative change in appearance.

    A Bicarb start-up prevents the loss of calcium hydroxide from the plaster, which preserves a dense (non-porous) surface, and no plaster dust forms. Instead, it converts calcium hydroxide WITHIN the plaster surface into calcium carbonate, creating a harder, denser, smoother, and more durable surface. And there is no increase of calcium hardness in the pool water.

    The Bicarb start-up program helps prevent the pH of the water from rising above 8.4, which generally happens to the pool water in new plaster pools, and is a common battle to control the pH when filled with average tap water. It does this by adding sufficient alkalinity (TA) to the tap water before filling, so that it is not aggressive to new plaster. Low alkalinity water creates two problems; it can dissolve calcium hydroxide from the plaster, then the high pH (12.4) calcium hydroxide dominates the pH of the pool water causing it to rise very quickly and very high (sometimes as high as 10.5). A minimum of 200 ppm of TA is required for proper pH control and buffering, and a higher TA may be needed if the calcium content of the tap water is low (below 200 ppm).

    The Bicarb start-up allows for fewer visits to control the pH. There is a reduced need for intensive brushing. Because the plaster surface is smoother and more durable, it stands up better to future acid washes and dirt and mineral stains are easier to remove. Dark colored plaster stays darker and does not become blotchy or lighter in color. Long-term esthetics is definitely improved. Acid start-ups can be one reason for colored plaster and quartz finishes becoming blotchy and lighter in color.

    Of course, some assume that scale will develop because of the high alkalinity level (having a positive LSI). But if the Bicarb program is done correctly, scale does not form. For over 10 years, many pool plasterers and service techs report having great success with the Bicarb start-up method. The entire pool plastering industry should adopt this start-up program to ensure quality and durable pool plaster.

    For proper plastering practices, see this post: ten-guidelines-for-quality-pool-plaster-t42957.html

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    Re: The Bicarb Start-up and Why it Works

    I don't see the need for a high alk start for any pool that has a high aggregate or polished finish.

    The one benefit I see is for plain or colored plaster is the the hardening of the surface cream.

    Leaving that cream over a non-marblite type finish like Diamond Brite, River Rok, Pebble Tec, Wet Edge, Hydrazzo, etc... prevents the cream from being removed to expose the aggregate of changes the polished look. That can't happen, that I can see if your start up procedure is followed.

    It has it's place and that is limited. It also presents material warranty issues for the contractor.

    Scott
    Owner of - PoolGuyNJ LLC
    Expert Pool and Spa Repairs, Renovations, and Augmentation. Helping people decide what is the right gear for meeting their needs. Expectations Set, Expectations Met, No Surprises.

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    Re: The Bicarb Start-up and Why it Works

    I agree that the Bicarb start-up program is more beneficial for typical new white and dark colored plaster pools.

    As for new quartz aggregate pools, some plasterers properly perform a well-timed hard troweling (without any water added), and do not leave a cream layer on top that covers up the quartz. The pool finishers appropriately remove the cream (or "fat"¯ as it is sometimes called) that collects on the trowel, and do not re-apply it back onto the plaster surface. The quartz aggregate is exposed sufficiently to allow the color to show. (My personal pool was done this way, it is eight years old, never been acid washed, and looks great with good color).

    There is still some pure cement exposed at surface (along with the quartz aggregate), and the Bicarb start-up will "carbonate" the cement portion without a loss of calcium, making the overall surface harder, denser, and smoother. A cream layer over the top is more likely to be weaker than a hard troweled finish.

    New Pebble finishes are usually washed to remove the cream (or cement layer) to expose the pebbles, yet there is still some cement exposed in-between the pebbles. The cement showing is also probably somewhat rougher than usual. (When dark colored cement is more porous, it is usually lighter in color). After the washing process is performed, the Bicarb start-up can still be performed to "carbonate" the cement that is at surface, which would help to densify it without removing more material.

    The problem with an acid start-up is that the surface becomes etched somewhat, and that creates a rougher and more porous surface. Afterwards, the surface still gets carbonated (by the alkalinity) over time, but the surface is not as smooth as it could have been with performing a Bicarb start-up instead. And a non-smooth surface means that it will look older sooner and attract dirt and stain easier.

    "Carbonation" of the cement does not add a layer over the top of the surface. It does not cover-up pebbles or the quartz aggregate.

    I am wondering what material warranty issues that a contractor would have with a Bicarb start-up?

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    Re: The Bicarb Start-up and Why it Works

    I disagree with the concept of allowing the calcium hardness level to increase "naturally" in new plaster pools. The fact that the calcium level is increasing is evidence that the water is removing calcium from the surface. That is not desirable nor what is best for a new plaster surface. That situation creates a more porous plaster surface and ages it somewhat, especially when that can be prevented. It would be far better to raise the calcium level to 200 ppm once the pH is under 8.0 within a few days of filling the new plaster pool. Also the TA should also be increased to help buffer the pH of water and to also help prevent the calcium (calcium hydroxide) loss from the plaster surface, which then increases the Calcium Hardness of the pool water.

    It is better when carbon dioxide reacts with calcium hydroxide in the cement and is converted into calcium carbonate (in surface) without any leaching or dissolving taking place. And when this reaction takes place, there is an increase in pH, but no increase in the TA level or the CH level.

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