Question about the Chemistry of Swimming Pool "Total Alaklinity"

[u/eesemi77]

I don't understand the swimming pool maintenance concept of "Total Alaklinity"

From my High School Chemistry: If I mix Calicum Hydroxide and HydroChloric acid together in a swimming pool then I would expect any excess Hydroxide ions to combine with any available H+ ions to form water. The end result should be CaCl + H2O

I would expect the reaction to happen almost immediately, yet Pool maintenance talks about Total Alaklinity acting as a ph buffer to reduce swings in the water ph over time. To my thinking, the ph of the pool water will be determined by the residual ions either OH- or H+. there's no magical "ph Buffer" that stores this "Alaklinity" without itself changing the ph.

What don't I understand about this reaction?

Edit: Background a recent change in the Pool maintenance company has seen my chemical use more than double (before just HCL) now HCL plus "Alaklinity buffer". Result, I use almost 3 times as much acid as I used to.

Edit2: if anyone else is struggling this is the most useful site I found

https://blog.orendatech.com/total-alkalinity-role-water-chemistry

As others commented it's all about the Carbonic Acid > Bicarbonate + H+ reaction

[u/lendluke]

I recently took over pool maintenance from a professional. Alkalinity IMO is a stupid term of the trade for pools. There is a buffer system with bicarbonate that can resist change to pH but eventually has CO2 leaving the pool needing even more bicarbonate.

Here is what I do: Ignore alkalinity, only add Sodium Bicarbonate if your pH drops excessively perhaps due to needing to add lots of chlorine. You'll find yourself using much less acid and base. 

It is pretty silly to add huge amounts of acid then huge amounts of base with the goal to increase "alkalinity" without changing pH.