Does this TA result make sense?

[Green Goblin]

I recently completed a water exchange to bring my calcium level down from. around 850 to 325.

As expected my CYA level and Salt levels fell similarly, and I'm bringing them back up.

TA was about 60 before the drain and has read 50 and 70 thus far when checking after the fill. pH right now is 7.4.

Most recent numbers:
pH 7.4
CYA 30
salt 1700
FC 3.5 CC 0
CA 325
TA 70

Does it make any sense that the TA didn't fall with the water exchange?

I didn't check the TA of my fill water, maybe that's the answer-- it's city tap water.

 

[wireform]

TA will be what the water is at the source

 

[Green Goblin]

TA will be what the water is at the source

You are right of course. I tested my fill water and the TA is 60.

I'm kinda old (but not that old) so maybe my memory is a little off, but I could've sworn that when I did water exchanges 2 years ago that I had to bump the TA with bicarb. Maybe I'm remembering wrong, but there is an open bag of bicarb in my pool supply cabinet.

Of course now I wonder if the fill water is different than it was then, but for the moment, don't look a gift horse in the mouth.