Heavy Rain Lowered Hardness

[DrainingIsExpensive]

Heavy rains this week lowered hardness from 300 to 150. I have heard low calcium causes etching. Calcium is sold out due to high demand from all the rain in this area. How long do I have before etching can start?

FCA - 8.68
TCA - 8.68
pH - 7.9
TA - 95
Calcium - 152
CYA - 85
Phos - 16

 

[sande005]

Read more here, it is more complicated than just the Calcium level: Calcium Saturation Index (CSI)

You didn't supply all the information needed, but guessing at temperature, etc., it looks like your CSI is very, very good.
Testing results are oddly precise for some items, so may not be trustworthy.

That is an awful lot of rain to drop the CA value that far - replaced 1/2 your water! (or the testing is very suspect!)

 

[ajw22]

If you did not run your pump for 24 hours at a high speed after a large storm the water is probably not well mixed and stratified with more rain water at the top where you can reach.

I would wait a few days and retest.

Etching happens over months, not days. If you do have low calcium you will have no damage if it takes you a week or even a month to raise it.

 

[DrainingIsExpensive]

Thank you. We had 22” in 3 days. Ran the pump 72 hours straight to lower my CYA, which dropped 23 points in 3 days. Good to know about the etching timeline but was battling chlorine/ph first now that the rain stopped. plan to dump 20 pounds of hardness in tomorrow.

water temp - 77.

test results combination of my test kit and store computer. sample mixed from 6 spots in the pool.