NO! NO! NO! This is not the time to add Borax.

Please read the threads on lowering T/A.

To raise your pH after lowering it to 7.0, you AERATE your water. You do this by leaving it uncovered, a gang of 10-12 year olds, fountains, waterfalls, or, pointing your returns at the surface. They all work but at different rates. But the aeration is the only way to raise pH without T/A going up with it.

T/A moves up and down with pH. So if you add borax you'll undo the good you did.

It's a ratcheting process.
You lower pH to 7.0 with Muriatic acid.
T/A falls with it.
You AERATE until pH goes back to 7.3-7.4.
Then use acid again to lower it.
Aerate again.

Repeat until your T/A is in the 80-120 range and your pH is between 7.2 and 7.8.