Add calcium?

[DrivenPT]

Hello again, TFP! I’m wondering if I should add calcium chloride to my pool or not based on my most recent testing.

Over the 6 months or so I’ve had this pool I’ve noticed the CH number slowly come down. We’ve had a pretty mild summer by texas standards but I have added probably 2500 gallons of fill water from the hose plus several substantial rains that have nearly overflowed the pool.

From what I’ve read on TFP, most people have high levels of CH in their fill water but that doesn’t seem to be the case for us as ours usually tests at 175 or so.

That said, I have a pretty hard time distinguishing between purple and blue on the CH test, so I always feel like my numbers have a significant margin of error to them.

Pool math tells me to add 24lbs of Calcium chloride to get to a CH of 450 but I’m wondering if that is more than I need. My CSI always seems to be in range with my current numbers, but I want to make sure I am not doing anything to compromise the plaster.

Thanks as always!

 

[PoolStored]

You want a minimum of 200 to protect the plaster. If your CSI can handle it, go 250 to give you a buffer with the rain/fill water.

When you do the test, keep adding drops until a drop no longer changes color (i.e. that last drop didn't make a change in the color). Subtract that drop. That should give your reliable results.

 

[ajw22]

CH of 250 is fine. No reason to raise it above 250.