Swg => MA => low alk

[JoyfulNoise]

- Most literature related to TA talks only about how it controls PH fluctuations. Given good overall numbers, what if TA was out of range? Any other concerns other than PH fluctuations? That was one of my initial concerns.

The total alkalinity of the pool water has two important effects - it acts as a pH buffer and it affects the saturation index of water.

Alkalinity is generally defined as the ability of the water to absorb hydrogen ions (acids) without the overall pH changing. In other words, the alkaline components of water (carbonates, cyanurates and borates) will shift their equilibrium distribution of chemical species in response to hydrogen ions being added or taken away from the water and thus keep the overall pH from changing much. When the pool water has no buffers in it, any addition of hydrogen ions or hydroxyl ions will cause the pH to change rapidly.

As for TA va CA, I always use Carbonate ALK whenever TA is requested because this is what I always understood must be done (CYA should always be factored in). For example to calculate CSI. But, again, I feel that most literature interchanges TA and CA or maybe expects one or the other but is not always clear. More importantly, the field in PoolMath app itself to calculate CSI is called "Total Alkalinity". So do the PH, TA, etc... adjustment tools. Should we be providing TA or CA? And if CA, should it not be changed to reduce the confusion? I've always wondered about this and maybe others also and others may just not know... Or maybe we should be providing TA? It's definitely a point of confusion!

It’s only confusing because the industry presents it that way. Saturation indices, whether the Langlier Saturation Index (LSI) or Calcite Saturation Index (CSI), only depend on the concentrations of calcium ions and carbonate ions in water. The calcium ion concentration is derived from the calcium hardness value and the carbonate alkalinity is derived by simply taking the total alkalinity and subtracting out the cyanurate alkalinity and borate alkalinity. PoolMath’s CSI calculations do all of the calculations for you so that all you have to do are basic measurements and input those standard test parameters.

In and of itself, the absolute carbonate alkalinity value has no meaning to a pool, total alkalinity is more important.

 

[AllenA]

Ok thanks. To get a clear picture of where i went wrong, I was double checking where it was that was indicating that CYA must be subtracted by 1/3 all the time (now I see this would have also included BOR). Couldn't find a clear answer. But I am glad that I won't need any of this using PoolMath and will then never bother with CA anymore.

 

[AllenA]

A quick update from my side for anyone else that may need this information.

The Lamotte folks were very kind and really took care of me. That said, the new TA reagent, 7039-G, has a 6 month expiry date. I was puzzled as the old reagent, 7038-G, always had a 1 year expiry date. The Lamotte folks informed me that since they had to release this new reagent quickly, they did not have enough time to test it for long periods of time and could only guarantee 6 months. The reagent may however last longer.

Allen