Do I need to add Calcium

[Jackiejkj]

We had very heavy rain last night. Over 5 Inches.

My CH went from 350 to 325.

PH 7.8
TA 90
CYA (reading yesterday 60)
FC 5.5 (I have added chlorine

 

[IceShadow]

I would recommend plugging your numbers into Pool Math and getting your CSI. What is your water temperature?

 

[Jackiejkj]

I do not know. I need to get a water thermometer.

I have a rough understanding of CSI. Can you explain the connection with calcium level?

 

[IceShadow]

I’m no expert but my understanding is that there’s a lot of factors regarding whether your water has potential to create scale buildup or on the other end leach minerals from a plaster pool and weaken the plaster. PoolMath takes all of these factors and calculates a CSI - calcium scale index. At 0 it’s balanced for that level of CH, TA, CYA, pH, water temp, etc. Too negative and you can get leeching. Too positive and you might get scale buildup.

I don’t think 25 ppm of CH is going to make much difference but the safest thing is to plug all the parameters into the app and see what your CSI is.