RiverbendPoolSupply.com - Todd's Blog - Episode 77

With all this rain I really needed to get out to the pool a second time this week and re-balance the water. Last night Plano got about 6" of rain in a few hours, combined with the 20" or so from this past month and that is over two feet of untreated rain water filling up my pool.
On Tuesday some of my balances were way out of whack, like the Calcium Hardness which had dropped to 160 PPM and the alkalinity at 40 PPM.
It is NOT GOOD to have low alkalinity and calcium hardness below 200 PPM because that sets the Saturation Index below -.3
Saturation Index tells us what our pool water desires to do. Below -.3 is corrosive water that will etch plaster, destroy equipment and corrode stainless steel. SI between -.3 and .3 tells us our water is sated and isn't corrosive or scaling. SI higher than .3 means the water is prone to scale.
With my chemistry balance the way it is with this rain water, my SI is -.62 - very corrosive. I need to raise the alkalinity and calcium hardness to correct this.
I added 10 lbs of Calcium Chloride to raise the hardness levels, and another 5 pounds of alkalinity up to raise the alkalinity levels.
I also added 1.5 pounds of cyanuric acid as that had dropped below 15. We will see on Tuesday what kind of balance we have. Keep dry and keep an eye on your chemistry balance this next week.