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Calcium Nodules In 1998, the onBalance team published a paper in the Journal of the Swimming Pool and Spa Industry (JSPSI) on calcium nodule formation. The paper provided the science and mechanics for the cause of calcium carbonate nodules developing in pools. It explained that delaminated...

Additional clarifications on the Bicarb (or Positive CSI) Startup. THE BEST PLASTER POOL START UP How a startup program deals with and prevents the detrimental process of “plaster dust” forming in newly plaster pools is the key in helping to preserve a quality plaster finish that will last 20+...

In recent years, calcium crystals have been forming during the winter at a higher rate in some newly plastered swimming pools. From the reports we have heard, this problem seems to occur more often in the northeast of the country. Apparently, pool builders, plasterers, and service techs involved...

Plaster colors can fade or turn whitish for a handful of preventable reasons. First off, scale can be deposited onto pigmented plaster surfaces by out-of-balance pool water. As is widely known, calcium scale makes the surface rough and turns it white, and acid washing is often the remedy...

Many of us may have had the unfortunate experience of adding soda ash to raise the pH and turned the pool water a milky white… in fact, we refer to it as “milking” a pool. Why does that happen and what does that do to the water? Well, the soda ash (sodium carbonate) is normally very soluble in...

There are two important issues involved when trying to achieve quality colored pool plaster that will remain durable, attractive, and the proper shade for many years. The first issue is to utilize superior workmanship practices to achieve good color, with minimal mottling, and no blotchiness...

An attractive plaster color (other than white) is often preferred by pool owners. However, it is very difficult for plasterers to produce a uniform and consistent color. The reality is that there will always be some minor shading (mottling) and variation in the color and can never be uniform...

Pool Water Balance Is Not (Always) the Problem (For this post, please consider the LSI as being the same as the CSI which is more familiar to TFP members. Pool industry people are more familiar with the LSI). For 50 years, the pool industry has considered pool water within an LSI (or CSI) of...

All pool plaster finishes should last 20 years or more. However, some last only 5 to 7 years, and some less than a year before the plaster surface deteriorates, discolors, and looks terrible. Why the difference? Very often, plaster quality. As we have pointed out previously, studies on pool...

Using the Calcium Saturation Index (also known as the LSI in the pool industry) as a guide for maintaining proper pool water balance and to protect pool plaster, including quartz and pebble finishes, has become a mainstay in our industry for good reason. Several experiments have been conducted...

Orenda Technologies has recently unveiled a new start-up program that is somewhat similar to the onBalance Bicarb start-up process. Instead of adding sodium bicarbonate, Orenda adds calcium (calcium chloride) to low calcium tap water while filling brand-new plaster pools, which also like the...

For pool owners, pool builders, remodeling companies, and pool plasterers that want the best chance to obtain a quality and discoloration-free pool plaster job (including white, color, and quartz aggregate pools), the link below is to an article in WaterShapes (a pool industry publication) that...

One of the arts or skills of the pool plastering trade is properly timing the troweling process. If troweling is performed when water is present on the surface of the plaster, forcing water back into the plaster paste causes excessively high water:cement ratios in the surface finish, weakening...

Just thought I would post this if appropriate for this forum and if there is interest. onBalance Cal Poly Pool Plaster Conclusions Shown to be Wrong Beginning in 2004, a series of plaster research studies were released by the National Plasterers Council (NPC), which they instigated and...

Some newly plastered pools (including quartz and pebble finishes) may develop either color fading, white soft spotting (also incorrectly called "spot etching" by some plasterers), white streaking (in colored plaster), calcium nodules, gray mottling discoloration (of white plaster), spalling...

This experiment below explains how white pool plaster can become blotchy gray, and also have white areas mixed into the gray areas. Both white pool plaster coupons below have been in water for one year. Sometimes the water was slightly aggressive (negative CSI), and sometimes the water was...

One would think that when mixing white cement with white limestone aggregate, the final pool plaster product would always be white. But that is not always the case. Unfortunately, white pool plaster sometimes turns gray (or grey) either immediately or a few months after the pool is filled with...

Contrary to some misinformation that has lately been floating around in the pool industry, high cyanuric acid (stabilizer) levels do not cause gray discoloration, or white spotting (“spot etching” as some incorrectly call it) in plaster swimming pools, no matter what. And there are several...

It is understood that muriatic acid can dissolve and etch a plaster surface. Therefore, why, after a plastering finisher works hard to achieve a smooth, hard, brand-new, hand-crafted, quartz pool-finish, would anyone immediately perform an “acid wash or acid bath” on that pool and that plaster...

Various metals in pool water should not be lumped together in how they react in pool water conditions. The following is my limited understanding regarding metals in pool water, and would welcome comments with different information. I agree that copper is less soluble at a higher pH than at a...

The myth: If muriatic acid is poured in a concentrated area, variously referred to as a column, slug, well or cloud, the alkalinity will be drastically reduced, but the pH will not drop as much as it otherwise would. And that if acid is added by walking it around a pool and evenly distributing...

What are calcium nodules? In swimming pools and spas, they are small mounds, bumps, deposits, or “slag” piles of calcium carbonate which are formed from material that has been released from the plaster. The small calcium nodules are rough to the touch, hard, and generally gritty. Nodules may...

There is a way to use pool water chemistry to calculate pool water volume without using the traditional geometric calculations. The geometric formulas are fine for pools that are traditionally shaped. However, when pools do not fall into these convenient shapes, a chemical method can be used...

The following information provides pictures and scientific evidence from the cement petrographers who performed “failure analysis” examinations on white spotted pool plaster cores. The first picture (above) is of a plaster core from the pool that had suffered from white spotting. Note the...

This article provides the basis and evidence for the recommendations to wait at least 6 hours before filling new plaster pools, using a low water/cement ratio for a plaster mix¸ and reducing the amount of calcium chloride added (one percent or less). Builders, Service Techs and Pool Plasterers...

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” (meaning for new plaster, the CSI should be at least...

The problem of plaster spotting has been an ongoing puzzle and controversy in the swimming pool industry for over three decades. The generally round, smooth-yet-unsightly white soft spots in new plaster pools have long been a source of contention among pool plasterers, and pool chemical service...

The concept of the “Zero Alkalinity” process (also known as a No drain Acid Wash) is to make pool water aggressive enough (by adding acid) to dissolve and remove metal stains or calcium scale from cement-based plaster surfaces, including quartz and pebble swimming pools. Unfortunately, this...

Technical side conversation split off of this topic. JasonLion I have been told by manufacturers of sand filters that sand "movement" and "agitation" especially during backwashing, will slowly and eventually smooth the rough edges of the individual sand grains causing them to lose some ability...

Plaster Discolorations – New white pool plaster can discolor (darken or turn gray) from adding excessive calcium chloride set accelerator, from late hard troweling, from thin and thick areas due to an uneven shell, etc. Gray (or grey) mottled discoloration (also known as “water entrapment” or...