Another quick CH level question

[poolurker5]

My current CH is 250, plaster pool about 7 years old. Was going to raise it to 350, but then read about testing the fill water first. Fill water CH is 200, which if I am reading everything correctly would not raise my level at all when replacing for evaporation during the summer.

So it looks like I am good raising it a bit, would 350 be a good target, or maybe 400 to get me through the summer? Thanks!

 

[PoolStored]

Leave it at 250...it is just fine. 200 will raise your CH...it doesn't go away with evaporation, only goes away with splashout, backwash or draining.

 

[revitup]

Leave it at 250...it is just fine. 200 will raise your CH...it doesn't go away with evaporation, only goes away with splashout, backwash or draining.

250? Even in a plaster pool? I thought CH was especially important to keep in the recommended range with plaster.

 

[PoolStored]

250? Even in a plaster pool? I thought CH was especially important to keep in the recommended range with plaster.

Yes. A plaster pool should have a minimum 250 ppm CH under normal circumstances. With fill water of 200, it will rise. 250 is fine.

 

[poolurker5]

With the fill water at 200, would this not dilute the pool water at 250 lower towards 200?

 

[mknauss]

With the fill water at 200, would this not dilute the pool water at 250 lower towards 200?

If you are refilling the pool due to evaporation, no, it will add calcium to the pool water and raise your CH.

If you are refilling because you removed some pool water by draining, splash out, or backwashing, then it would reduce the CH level.

 

[poolurker5]

got it! I checked my records thru the past few years, and the pool typically runs 300-400, with this time last year at 375. This is the first time at 250, must have been a bit more rainy these past few months.

 

[mas985]

What matters more for a plaster pool is CSI rather than just CH alone. TA and PH also affect how aggressive the water may be. As long as CSI > -0.6, the plaster will be fine.