ive got a pro 7 thermopure. it fills up a reservoir with normal tap water, it then cuts off and what ever is in there is then pumped through RO, resin, filters like normal. When the reservoir is empty, it cuts off the circulation through the RO and filters and starts all over again. Thats the basic gist of it anyway. It hasnt let me down, the only thing is, it just costs a bit more on resin.
Hope this helps
