Low TA Issue

[FlDave]

I could use some guidance here.

Before I start, this pool is about a year old. Things have been otherwise stable except for it's constant demand to add acid because of rising PH.
Recently (stupid me) left the hose on over night and I estimate that I replaced nearly 15,000g of water by the time I noticed.
I was able to get things to quickly bounce back since it was mostly the CYA and FC that was diluted with a slightly higher PH (8.4).

Here's my latest test:
FC: 3
CC: 0.5
TC: 3.5
CYA: 60
PH: 7.2
TA: 40

So, I was previously using the ATC PH tester, I continued to add Muriatic acid, only to realize last night that according to multiple drop tests, the PH was a full point off.
I now realize it needs to be re-calibrated but an 8.4 reading was really closer to 7.2-7.4 and after trying to reduce it...the PH was likely closer to 6.2-6.4 at times after addition of acid.

My biggest issue:
Kids hair is turning green, eyes are red, and all complain of itch skin the next day.
Is it possible that the low TA is creating a corrosive environment and causing either the Gas Heater or Heat Pump to introduce copper?
I've never used any copper based algicides or otherwise in the pool. I'm assuming a copper issue because of the green hair, but these kids swim in 3 different pools each week and I can't pin-point if it's mine.

I've searched enough on here to assume a TA of 40 is not good and I should really target 60. Does this sound correct?
I'm estimating an addition of 5lbs of baking soda.

I will not add anything until I get everyone's valued insight here on what I should be doing.

 

[ajw22]

You problem is not your low TA but likely you crashing your pH for a time.

Green hair indicates copper in the water. Take your pool water to a pool store and get it tested for copper.

If you have copper in the water then you will need to drain your pool to remove it. And plan to replace the heat exchanger in your heater eventually.

Copper in Pool Water - Further Reading

www.troublefreepool.com

 

[FlDave]

Allen,

Is it that bad? Can I really kill an exchanger that quickly?
Also, would that be just the gas heater or the heat pump as well? If this is the case I'm tossing the digital ATC because it's a costly mistake.

 

[ajw22]

Is it that bad? Can I really kill an exchanger that quickly?

Depends how low a pH for how long.

If you have copper in your water it came from the heater. At a minimum the heat exchanger is thinner then it should be and will fail sooner.

Monitor your heater for leaks or unusual behavior.

Also, would that be just the gas heater or the heat pump as well?

The gas heater uses a copper heat exchanger. I think the HP uses PVC but I am not sure.

If this is the case I'm tossing the digital ATC because it's a costly mistake.

Every pH meter needs to be regularly calibrated and checked against known pH sources. I know my tap water is ph 7.6 and if my pH meter does not read that I know it is time for a calibration.