ph keeps falling

[KurtV]

TA is 110, this is in the right range, correct?

Yes, but unless your calcium level is too high you can probably raise it a good bit without it causing any problems and raising your TA will help keep your pH up.

An alternative is to aerate your water somehow. That will also raise, or at least keep steady or slow the fall of, your pH. Do you have any water features or fountains that you could use for aeration?

What is the calcium hardness of your water?