High pH in a trichlor pool

[safeguardaquatics]

I have a 3700gal pool on a trichlor system and we just cannot get the pH down. Trichlor is highly acidic so we should be having the opposite problem. Any ideas why this is happening??

FC: 7.5 (high because we opened up the trichlor flow in an attempt to bring pH down, it didn't work)
CC: 0
pH: 8.0
CYA: 90 (high for the same reason as FC above)
TA: 90
CH: 340

This pool is adjacent to a much larger liquid chlorine pool with a low TA and low CYA so our plan is to exchange the water between them to sort of give the small pool a good re-start with good water chemistry. I am a CPO and even asked my CPO instructor what could be causing such high pH and nobody has any clue.

[Denniswiseman]

Aeration raises pH (fountain, spill over, infinity edge, etc)
For every 10 ppm Free Chlorine (FC) added by Trichlor, it also increases Cyanuric Acid (CYA) by 6 ppm.
For every 10 ppm FC added by Dichlor, it also increases CYA by 9 ppm.
For every 10 ppm FC added by Cal-Hypo, it also increases Calcium Hardness (CH) by at least 7 ppm
High CYA renders your chlorine ineffective
With a CYA of 90 you need a target FC of 10-12,you are better off using liquid chlorine rather than trichlor