This might been the thread
http://216.187.96.54/vbulletin/showthread.php?t=27193&page=1&highlight=float
Still have my ro/di direct to float in the sump. After more than a year of running my unit with no maintenance (yes, I over used the filters and resins) highest I seen my TDS was 20. Changed filters and resins back to low TDS.
btw, just went downstairs and ran a few oz into a cup from the float, got a TDS of 5.