I work at a high end hotel with several indoor spas that have both waterfalls and jet pumps. The controllers are Chemtrol boxes with both sanitizer Bromine(solenoid) and pH feeders(stenner pump). Both feeders are set up on proportional feed.
The spas are just under 2500 gallons. The issue that I am having is that in order to keep the alkalinity at ~80 I am having to add over 1kilo of NaHCO3 daily. This causes my TDS to rise over 1000points in a matter of about 10 days. Typically, I drain and refill at about 14 days or 1500TDS. Start TDS is ~400. This 4 day decrease has caused a substantial rise in water costs though.
I have taken to adding 500g each day to reduce this TDS rise and the alkalinity levels off consistently to about 40-50 at the end of the day.
So, my question is, "Is it necessary to maintain the recommended TA(80-120) with my chemical feed setup?"
My conclusion is no, as it seems that TA is largely a pH buffer that with proportional feed control is not quite as critical. I would like to get some feedback from some others though as it seems that I have begun to trod uncovered ground.