Has anyone else heard of this? In some AFO classes, put on by some Cal Hypo dealers, the recommendation is to raise hardness levels to maintain a hardness-alkalinity ratio of 4:1 to 6:1 or even 10:1. This is not part of the course, but was more an offshoot discussion of balancing pools, and what index is best used – the LSI, or the Rhyzner. Many instructors often put in their own tips to help keep the class interesting, but this one just got me confused.

Let me explain, and in order to get this right, I’ll quote from what one instructor/dealer told me, “These ratios act as a catalyst for efficient CO2 use, and for stabilizing both the Alkalinity and Calcium Hardness levels. The vehicle for the carbonate ion is to ride on the calcium. Not enough calcium, and the CO2 just off-gasses more readily.”

When asked about any details on the chemical basis of the theory, nothing is given except that it was found by some long forgotten chemist, whose name they can’t remember but who figured this out.
Sounds plausible, except for a few red flags that pop up here and there.

Granted, calcium plays an important role in pool chemistry and in balance equations. And I’m not against going slightly beyond recommended ideal limits for calcium of 200 to 400 PPM’s, as long as you compensate for it by lowering the pH and alkalinity. And I do know of some pools that claim that the magical number for them, for calcium hardness, seems to be around 500 PPM. They say it seems to lower their acid use and evens out the alkalinity…. so I’m not discounting it, but am wondering if it coincidental with something else happening in the pool. In fact, I myself prefer to start out at 500 PPM’s, as I like to run lower alkalinity spans of 60 to 75 PPM’s to help with aqueous CO2 off-gassing. The ratios of 4:1 to 6:1 isn’t all that outlandish, as many pools will still be under 500 PPM’s of calcium using those ratios.

It’s just that higher ratio’s, which were inferred to in that discussion, of being well over 500 PPM’s that bothers me, and makes me wonder if this could all be part of their sale pitch of “High Calcium Chemistry”…in that Cal Hypo is good, and liquid chlorine is bad mentality. There is enough chemistry out there that shows that Aqueous CO2 off gasses more so in a direct relationship with low pH, and with the rise in alkalinity, temperature, and aeration. Basically, higher pH and lower alkalinity levels will help in lessoning CO2 off gassing, and thus would have an effect of stabilizing the pH somewhat. I just don’t see where “High” Calcium levels above normal recommended ranges has to play in the role of efficient CO2 use, and stabilization of both alkalinity and calcium levels.

I would just like to hear of someone who can explain some of the chemistry behind this “magical” relevance of high calcium levels as being a necessary carrier molecule for this, or that very high levels are required or even beneficial. If there really is a relevance, then what is the minimum, or guidelines for this to occur?