My TDS is 220 out of the tap and 001-002 after the RO/DI is the best I've ever been able to get.
My unit runs 70gpd and I run it to two float valve and have a auto shut off valve on it. The auto shut off valve stops the waste water from continualy running when the good water supply is stopped in both buckets by the float vlaves. One bucket it 38 gal for water changes, it fill to about 33. The other is a instant ocean bucket witha float vavle halfway up which is used for the auto top off by the liter meter.
It does sound like your unit is improperly set up, make sure it has all the lines running correctly and the correct gpd reducer is in place.