Managing TA with high levels in fill water

[cjs]

Here are my current pool readings:

FC 6
CC 0
TC 6
CH 300
TA 70
pH 7.2 (just lowered pH and TA to this level, aerating now back up to 7.6
CYA 60 (recently stopped using trichlor, bringing this down over time with rain and backwash)

I have been working for a while to get my TA down, and it's not been going all that smooth. Today, I tested the TA of my fill water, and it comes in at about 410!

Here are my questions...in order to maintain my TA moving forward, if I add approx 2% (which is about 285 gal in my pool) refill water with TA of 410 (figure that to be just over an inch due to evaporation), how much will the TA go up in my pool with the levels mentioned here.

More to the point, should I add acid as I fill the pool, just before, or after I fill the pool (how long after if so), or is there a better way to do this to offset the TA increase?

Is it better to top off with less water more frequently, or more water more frequently...or does it matter?

I have constant flow from a spa spillover, so plenty of aeration going on. I'm working toward a target TA of 60...any thoughts on this given all that I've said in this post?

Thanks for your insights,
Craig

 

[JasonLion]

Adding 2% water with a TA of 410 is going to raise TA by about 7.

It might not be possible to maintain TA at 60 with fill water that has such a high TA level. Probably you should just bring the PH down to 7.2 every time it gets up to 7.8, and then see where the TA ends up. That might be the best you can do.

If you haven't already, you might want to think about adding borates. That will reduce the frequency with which you need to add acid.

 

[No P in my ool]

My fill water is also over at a 400 TA. I keep mine at about 100 to110 and added borates. Even with a SWG my PH stays between a 7.4 -7.6.