CSI too low for plaster?

[LandCruiser]

Still battling the new to me old plaster pool at the home we purchased. My PH is ultra consistent, doesn't drift, stays rock solid at 7.6 (water temp is still about 57F). My alkalinity is 50, also very solid.



My Csi is -.52 currently and has been low since we moved in January 2022. I'm hesitant to touch Alkalinity, I did that in my above ground pool and had to deal with unstable Ph has a result of getting TA too high. Seems like I could probably inch alkalinity up a little though? I could also raise calcium?

Just not sure if I should be concerned or not since the rest of my levels feel very stable.

 

[Flying Tivo]

If it aint broke, Dont Fix it! Pools will find their own PH/TA levels.

 

[mknauss]

I could also raise calcium?

What is that level? Does your fill water have calcium in it? Do you add fill water during the summer or rely on rain water?

 

[LandCruiser]

What is that level? Does your fill water have calcium in it? Do you add fill water during the summer or rely on rain water?

Sorry, CH is 240. I don't believe my hose water for fill is very hard, my TDS in my tap is about 40 (very good water here). Very little rain in Northern California lately (drought).

 

[mknauss]

Even if your tap water is 40 ppm CH (test it), then if you are using that water for fill water due to evaporation, your CH level will rise, albeit slowly. So you might add enough calcium to get to 300 ppm CH. Or, You can use cal-hypo to chlorinate with for several months and that will add calcium.

 

[rstrouse]

-.51 is pretty low but your CSI will rise as the temperature of the water increases. During the colder months I run my TA a little higher to keep CSI in check. Bear in mind I also have a demand based acid dosing system that automates the pH levels. As you can see last night the water temperature dropped to 59F and the CSI dropped to -.24. TA is much easier to get rid of than CH but mine has been pegged at 400 for the last couple of years.