It's a company called purewaterclub.com. I get 4tds after the di. Before di I get 69tds
That's a problem for an rodi unit to do that. Are you sure your DI resin isn't depleting too fast? Either you have harsh water, the sensors aren't calibrated properly, or there's something else going on. You should flush the system, until the tds gets to it lowest point without the flow restrictor engaged, before and after use. Try to use a
flow restrictor that can be opened and closed. Some are the capillary type and are inside the drain tube. No good.
It sounds like a lot of tds creep is building up. Also, new membranes are supposed to be run for an hour, according to BRS, before being put into use. I would also recommend getting a
3-way valve for after the membrane so your flush water doesn't go into the di resin. Then have the flush end of the valve combine with the regular waste water output with a
diverter. Just use it to combine the 2 sources into one before the drain.
Do you have chloramines in your water? If your carbon is depleted it will let chlorine and chloramine through and will damage the membrane. Also chloramine needs a specific carbon block.
You should probably have 2 DI canisters to clean up the 4 TDS because who knows what in it until it's tested for. Are they color changing DI resins?
Did you run tests on your freshwater supply before and after the rodi unit? Also, having a TDS pen to dip in the water is more accurate than inline ones. Though the inlines give a good base for different sections of water filtration along the way.
Your tank is young. Let it do its thing and concentrate on the rodi system. Something is off there.
You also mentioned getting only 300 gallons. But that is 300 gallons of good water and probably another 900 of water down the drain with a 4-1 ratio. So it's actually 1,200 gallons that passed through the system.