No? So why have it or change it? What’s the function?The prefilter shouldn't affect the TDS.
We never wire 110 or 220 to a float switch - only low voltage as a safety precaution.For some I believe it's ignorance, or possibly cost savings. The cheapest system I've seen is wired against electrical code and uses one leg of 240V run through a float switch with the other leg wired live all the time to the motor. It works, but it's not proper, and with the way it chatters the motor every time it comes on it reduces the pump motor life.
The membrane manufacturers spec a 5 micron (or below) prefilter.The prefilter keeps large particles out of the membrane. A lot of the systems I've seen have the prefilter before the inlet solenoid. Most are 5 micron filters, I usually use 1 micron if I can find them in the right size. Years ago I had a customer who was having membranes foul after just a couple months, so I tried a .35 micron prefilter and it solved his problem...until he let the filter get plugged and he tried to blast it clean with high pressure.
The membrane manufacturers spec a 5 micron (or below) prefilter.
Also - we have he sediment filters you need always in stock.
Russ