Calcium hardness low normal range


May 29, 2020

I switched over from Dichlor to 10% liquid chlorine and have been keeping the chlorine levels at recommended levels between 3-5 And pH between 7.3-7.5 since my initial Calcium Hardness before switching was 450.

My latest test results today after two weeks of the switch are
pH 7.8
FC 3.5
CC 0
CH 300
TA 80
CYA 40

Honestly was surprised that my CH dropped but I’m assuming that was due to the switch from the dichlor.

Pool math said I should bring it up to 450. I still have some dichlor pucks I can use for the in-line chlorinator. Should I just keep dichlor running at a low rate to keep my CH level at optimum. I really don’t want to risk getting calcium scaling again but also don’t want to go the opposite way.



Mod Squad
TFP Expert
Bronze Supporter
May 3, 2014
Laughlin, NV
Dichlor does not have calcium in it. Only CYA and chlorine. There are no such thing as dichlor pucks.
They do make cal hypo pucks. And those do add calcium. But do NOT put them in the chlorinator. ONLY trichlor pucks go in that. Cal Hypo pucks could cause an explosion.

Your CH of 300 is fine as it is. If it gets down to 250 ppm, then add calcium.

Your dropping CH can only be due to water exchange (overflow from rain) or testing error.
  • Like
Reactions: Leebo