Fiberglass Calcium requirements from Leisure Pools

[Jonovision]

I found this document online about PH and Calcium levels for Leisure pools fiberglass maintenance and is sort of opposite of TFP and what is mentioned on the forums:

pH 7.2 to 7.4 • Total alkalinity between 80 to 120 part per million

Calcium naturally occurs in water. Different areas of the country have higher and lower levels of calcium in the water. The higher the calcium concentration in the water, the more prone the pool is to calcium leeching. When the pH is maintained between 7.2 and 7.4 the calcium is balanced in the water. Calcium levels should be maintained between 80 – 120 parts per million. When the pH rises above 7.4, calcium begins to leech out of the water and cling to the swimming pool surface. The higher the pH is allowed to go, the more pronounced the calcification can become. Obviously the problem occurs more often in areas with higher natural concentrations of calcium in the water.

All that is required for calcium to fall out of solution creating a layer of scale is a pH of 7.4 or higher and calcium hardness over 150 parts per million. The higher the levels, the more pronounced the problem will be. The current guidelines being used for adding calcium to water are based on concrete pool guidelines. There should really be no reason why you should add calcium chloride to your water for a Leisure Pools® swimming pool. Please be aware that many pool stores, mass merchants, and mobile service companies do not know how to correctly care for fiberglass pools.

So what should we follow? I have it currently at 290 ppm and TA at 70.

 

[Texas Splash]

So what should we follow? I have it currently at 290 ppm and TA at 70.

Based on the education and rationale provided here at TFP, you have to decide who you wish to follow - TFP, pool stores, manufactures, etc. We go into great detail at TFP about those "generic" recommendations and why they are published that way. For example, why try to force such a low pH with an elevated TA? Do they not understand a TA of 100 - 120 will promote pH rise? You'll never be able to maintain a pH at 7.2 - 7.4, nor should you. As to the discussion about calcium not required in a FG pool, we don't argue that from a leaching position. But what about potential (Cobalt) staining? TFP recommends a minimum CH level primarily for stain protection. You could also argue that a minimum CH is also beneficial for some auxiliary equipment. A pool owner's method of chlorination also accounts for TFP recommended levels.

TFP accounts for many variables that these generic publications do not.. Your current numbers of 290 and 70 are fine.

 

[JoyfulNoise]

This is a demonstrably FALSE statement from their literature -

All that is required for calcium to fall out of solution creating a layer of scale is a pH of 7.4 or higher and calcium hardness over 150 parts per million.

The potential to scale calcium is controlled by pH, TA, CH and temperature. Water that has a pH of 7.4 and a CH of 150ppm almost always has a negative saturation index (either CSI or LSI) unless the TA and temperature are extremely high. Thus calcium scaling is not possible (they even use the term “leeching” incorrectly ).

You have to determine what is right for you and your pool. Maintaining any chemical parameter at artificially, and unnecessarily, low values will only cause you to chase your tail. The manufacturer clearly doesn’t understand the science but that doesn’t mean you have to go along with their foolishness.

 

[Jonovision]

Thanks for reaffirming the TFP methods. I also didn't understand why it would scale as my CSI is usually slightly negative. Regardless, hopefully this helps others when they come across these outrageous claims.