Imagine, service techs: from day one, you maintain the pool water in perfect balance, yet get blamed for causing various plaster discolorations or defects. That is not a pleasant thing to deal with, especially if you are being told to pay thousands of dollars to re-plaster the pool.
Yes, some plastered pools (including quartz and pebble finishes) may develop either white spotting and streaking, calcium nodules, gray mottling discoloration, spalling (flaking), severe craze (check) cracking, or early deterioration within a few months after being plastered, and service techs or pool owners (or whoever maintains the water) have been incorrectly blamed for those plaster problems.
Generally, it will be claimed that the pool water has been “aggressive” at some point in time, even if the water has never been aggressive. But more importantly, the above plaster problems are not caused by aggressive water. Cement and plaster studies have identified improper workmanship practices as leading to those problems developing.
So why are these unfair accusations happening? One main reason is because the National Plasterers Council (NPC) doesn’t do anything to stop it, and in some ways, enables it to happen.
Let’s examine this issue. The NPC and some plaster inspectors define “balanced” pool water within very narrow parameters, but without any supporting science to back it up. The NPC states that all water parameters (pH, TA, CH) must be maintained within the APSP’s “Ideal” ranges to be considered balanced, and disregard the APSP’s “minimum and maximum” standards. On what basis do they require that?
For example, NPC literature essentially suggests that pool water with an alkalinity of 70 ppm is considered to be out of balance and aggressive, even though the APSP has established 60 ppm as the minimum alkalinity standard. Even if the other water parameters make the LSI balanced, the NPC still considers that water “aggressive” and able to cause plaster problems.
Yet, contrary to that, the NPC says it is okay to use “acid treatments” on new plaster surfaces to remove stains and discolorations as a remedy. Yet, acid treatments are 10,000 times more aggressive (-4.5 LSI) than pool water with an LSI of -0.2 which the NPC claims is too aggressive.
And it doesn’t stop there. There are plaster reports that falsely blame high CYA, high TDS (salt pools), Trichlor, high chlorine, carbonation, or ionizers for the some of the above plaster problems. Again, the NPC has no science or study that supports such claims. Even rebar (rust) staining has been claimed to be caused by “imbalanced” water chemistry.
So if you as a service tech are being blamed for causing one of the above plaster problems, and a NPC inspector or plasterer gives you a copy of the NPC Technical Manual, a report by Arch Chemical or Cal Poly (NPIRC), or any other literature, and suggests that it proves whatever it is they are claiming; don’t be hoodwinked or intimidated. Those reports don’t prove that out-of-balanced water causes those problems. In fact, they mostly prove the opposite.
Also, if your chemical start-up process is questioned by the plasterer because the tap (or fill) water was aggressive, we suggest that it is the plasterer’s responsibility to see that the tap water is balanced before it used to fill the pool. Let's understand that the vast majority of the damage (uniform etching) that is caused by aggressive tap water occurs while the pool is filling; and before you show up at poolside (after it is full) to balance the water.
So while the NPC leaders seemed to be focused on blaming water chemistry (outside very narrow parameters) for various plaster problems, they are also refusing to adopt simple and general workmanship standards and limits on plastering practices to ensure quality, discoloration-free, defect-free, and long-lasting pool plaster. Very important issues such as water/cement ratio, wet troweling, late hard troweling, and calcium chloride limits, are not even mentioned in their new ANSI Plaster Standard.
Sadly, some plasterers currently advertise that plaster only lasts 5 to 10 years. But not long ago, plaster used to be promoted as lasting 20 years. In reality, it still can and does last 20 years when quality workmanship is performed. It’s not difficult to figure out who benefits and who is harmed when plaster finishes don’t last very long.
It is unfortunate that poor quality plasterers are being aided to avoid being held responsible for bad plastering work and results. That needs to change for the betterment of the swimming pool industry.