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Frequently Asked Questions
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This is a short list of our most frequently asked questions. Be sure to check back often as we will be adding to it on a regular basis.

For more information about NPC, or if you need support, please contact NPC at mail@npconline.org or 847-416-7272.

 

When I turn the light on in my new pool I see lumps and waviness in the floor of the pool, is this normal?

I have an older pool that has 20 year old plaster in it. Are there better surfaces that have come to the market?

My plastering company recently advised me that a problem in my pool surface was attributed to “low carbonate alkalinity.” What is “Carbonate Alkalinity?”

My pool plaster is approximately two years old. For the first 18 months the white plaster looked fine, but now is slowly turning blue, blue/green and black. What is this?

My white plaster was fine for over one year. I had sod (grass) put in around the pool and a new wrought iron fence put in. After my back yard makeover, I noticed small brown spots on the plaster and on my pool cleaner called a Poolvergnuegan, which is also called “The Pool Cleaner.” The brown spots are on the pool hoses and mainly on the floor of the pool. What are these small brown spots?


When I turn the light on in my new pool I see lumps and waviness in the floor of the pool, is this normal?

Plaster and all cementitious interior pool finishes are a hand crafted product. In section 3.1 of the National Plasterer Council Manual 8th edition it states - General Tolerance Determinations: "Observation , using the swimming pool light at night, or other sources of light that shine across the surface, instead of upon the surface, are not considered a fair representation of the surfaces true appearance. Certain angles of light will grossly exaggerate imperfections and/or the waviness across the surface finish." As it says some fluctuations and waviness in the pool surfaces are normal. If you cannot observe them in normal daylight viewing conditions it is probably normal.

I have an older pool that has 20 year old plaster in it. Are there better surfaces that have come to the market?

Yes- surfaces such as quartz, mini pebble, and pebble and polished surfaces are now available throughout the United States. Many of these products also have special modifiers in them such as pozzolans or polymers which enhance the long term durability of these surfaces. You should ask your remodeler about these types of surfaces. 

 My plastering company recently advised me that a problem in my pool surface was attributed to “low carbonate alkalinity.” What is “Carbonate Alkalinity?”

Carbonate alkalinity is also known as corrected or adjusted alkalinity. The three most important water chemistry parameters necessary to have “balanced” water are A) pH, B) Carbonate Alkalinity and C) Calcium Hardness in their correct ranges. Most test kits test total alkalinity, but carbonate alkalinity is calculated by taking approximately one third of your stabilizer or cyanuric acid content and subtracting it from your tested alkalinity. Remember, only carbonate alkalinity can be used to calculate the Saturation Index of your water and whether it is in balance.

My pool plaster is approximately two years old. For the first 18 months the white plaster looked fine, but now is slowly turning blue, blue/green and black. What is this?

You are probably getting copper stains. Take a piece of #80 wet/dry sand paper or a diamond hand pad, and see if the stains will sand off. The four most likely sources of copper metal are 1) fill water, especially well water or trucked in water. 2) Improperly maintained pool water that becomes corrosive and attacks heat exchangers and other metal components. 3) Certain ionization systems that are not maintained properly and contain copper. 4) Copper based algaecides that are improperly dosed, most often to kill algae.

My white plaster was fine for over one year. I had sod (grass) put in around the pool and a new wrought iron fence put in. After my back yard makeover, I noticed small brown spots on the plaster and on my pool cleaner called a Poolvergnuegan, which is also called “The Pool Cleaner.” The brown spots are on the pool hoses and mainly on the floor of the pool. What are these small brown spots?

Based on your description the brown spots are either a) small metal particles from the installation of your wrought iron fencing or b) fertilizer stains often associated with iron or ammonium sulfate type granular fertilizers. Usually these small spots will sand off with a piece of wet/dry sand paper or a diamond hand pad.

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