My first question here, but I have not found any information anywhere that has been helpful. I have an ingound plaster pool that is now 1-3/4 years old. It is a saltwater pool that holds 19,500 gallons and I have not had any issues with it to date. No algae, no cloudy water etc. I have a Taylor K-2006-C test kit that i use to moitor the levels. The equipment is all Pentair with a 520 cartridge type filter. The pump, an intelliflow, runs 12 hours a day and I also have an intelliph acid injector that maintains the ph at a constant 7.4.
My trouble is that my TA is constantly falling. I have to add about 5 to 10 lbs of sodium bicarbonate every month to month and a half. I have not added salt to my pool since it was first filled and I constantly show high salt levels. I am making the assumption my salt levels are increasing from the constant additions of sodium bicarbonate. We have two decorative sconces and a 4' sheer decent waterfall that run a fair amount on the weekends only, and I am thinking this might be causing my TA to drop like it does. Can anyone confirm my assumptions made above and does anyone have any suggestions?

Plater Pool
19,500 gallons
FC 3.4
CC 0
PH 7.4
TA 90 (currently)
CH 450
CYA 60
86 degrees