In ground pool - 25,000 gallons - 4 years old.

To date little problem with water clarity etc. Noticed my TA is now 160-it is usually around 120. Other readings are as follows:

CL: 10 (kept high due to CYA reading)
PH: 7.6
CYA: approx 100.

I know that an ideal TA is between 100-120. However I have also read that with a high CYA you need to deduct one third to one quarter of your CYA reading from your TA reading to get a true TA level. This would mean my TA is "really" around 130. However even at 160 should I be worrying about it as my water is clear, the PH does not bounce around and I have no algae. The pool shop says I should be putting in 4 pints of muriatic acid for 2 days to lower my TA, but isn't this going to send my PH shooting downwards?

Many thanks for any advise.