reading is not what you really need to be testing. You need to test your water for nitrates, phosphates and silacates. If you have a reading of any one of these then you need a Di
housing added to the unit.
is total disolved solids, it does not say if the solids are good or bad and the 3 items listed above are not picked up by a TDS
Don't get me wrong you want a 0 TDS
out of the DI
unit, this tells you that it is working properly and the filters are good. IMO
you still need to test the water for NO3
and silacates because even with a low TDS
you can have high levels.