Saturation Index vs. high Ph vs. low calcium

[Pool Mom 9]

Hello, I'm a new pool owner and boy I wish my dad had a pool because I know he would have all these answers. So far, TFP has been an amazing resource because I really want to understand and maintain my pool chemistry myself. I have only had the pool for about a month and the testing strips were all over the place so I purchased a Taylor Testing Kit 2006. My first results showed high Ph and very very low calcium index. When I messed around with the saturation index calculator though it looks like correcting those might worsen my Saturation Index. I know that isn't a huge deal b/c I have vinyl but I am worried about my concrete deck. My results today were as follows:

Ph 8.0 (acid demand test was 1 drop to bring it to 7.6)
Chlorine 4.2ppm
Combined Chlorine .4ppm
Total Alkalinity 120ppm
calcium hardness 40ppm
Cyanuric Acid 48ppm
Saturation Index -0.14

My thought based on the Taylor test kit calculations was to add in 1.15pt muriatic acid and 14.4lbs calcium chloride but when I guesstimate what that will do to my numbers it worsens my saturation index. Any help or guidance would be much appreciated!!

 

[bdavis466]

You can dismiss low CSI numbers with a vinyl pool.

Does your water foam up? I ask because your CH is very low.

Regardless of CSI, the pH should not be allowed over 8 and really shouldn't be below 7 (especially if you have a heater).

 

[Pool Mom 9]

That is interesting you ask about foaming. I have developed bubbles coming out of my return jets and assumed I had an air leak but wanted to get my water chemistry right before I asked PB to check it out. I wonder if adding calcium will take care of that. I am going to rerun tests tomorrow and then add acid and add calcium the following day

 

[bdavis466]

Low calcium levels below about 150 are prone to cause the water to foam. There really isn't much need for you to raise your calcium much above that level.