sorry took so long to get back, but I have a different unit now. got a Typhoon extreme III and added 2 DI, TDS meters: 1 tap in, 1 RO out, 1 @ #2 DI out, and 1 pure out. plus I have a hand held . Tap is 250 TDS, give or take. after RO it is about 4 TDS. Since getting the new unit with add ons...