Honestly what got me was I was burning through di resin in about two weeks. When I contacted awi they told me that was right with my incoming TDs. I never had that problem with other units. When I switched to spektrapure I used there pre loaded di resin and I've gone six months with 0 TDs.
Also, this happened with two units for me. I thought I had a bad unit for whatever reason so I got a brand new one and it was the same thing. But there are tons of people without that problem so I really never understood it. I just know my spektrapure rocks and I'm very happy with it.