Quote Originally Posted by wapate View Post
First, I want to thank you for starting me in the right direction. I have lowered my PH gradually, now 7.7, the TA (96 adjusted) has not changed much, so I'm heading the right way. My FC is 3, my CYA is 30 & my CA is 150. If I understand the S.I. correctly, that puts me close to 0. My goal now is to maintain that.

CYA is too low calcium is too low for a plaster pool Adjusted TA is hot very useful, no matter what the Taylor book says!
Wanted to clarify something I said earlier. When I stated my pool looked good to be 14 years old, I was not referring to the PH looking good. What I meant to say was that for my pool to look like it was plastered yesterday, and the fact I have never had a build-up in my SWG, the chemicals must have been close to correct. I've never seen a post claiming a pool can be way out of balance and have a finish like I do after 14 years.

Thank You Again.........
If your calcium has always been that low it probably means that you have not had scaling conditions but had aggresive water, which would also explain no calcium buildup in the cell. Also the Langelier SI that you are probably using if you are using the Taylor WaterGram is not really applicable to open systems like swimming pools, it was desgined to predict scale buildup in closed boiler system.

IF you want to get your water balanced then:
1. get your CYA up to 75-80 ppm and keep it there
2. make sure the FC never drops below 4 ppm
3. lower the TA to 70 ppm
4. Keep your CH between 350 and 450 ppm
4. Keep the pH ABOVE 7.5 and BELOW 8.0
This will keep your Calcium Saturation index within an acceptable range for water temperatures from abut 72 degrees to 90 degress

If you decide to add 50 ppm borate for the secondary pH buffer (it tends to keep the pH around 7.7-7.8 for a longer period of time than without borate) and for the algaestatic properties (a good idea since you have had mustard algae) then keep the CH closer to 450 instead of 350 to maintain the calcium saturation index.