I can only speak for the clinic where I work, I know there are some horror stories out there about some clinics.
My clinic has 16 chairs divided into 2 bays. Each bay has 1 tech for each 4 patients. One nurse for each bay. The techs basically do all the technical work - at my clinic, the nurses help out a lot, especially putting people on and taking them off. The nurses are primarily responsible for initial and post assessments, double checking settings, troubleshooting, giving meds. I'm still on orientation (it's a 3-4 month orientation process), so right now I'm with a tech. I know the nurses do lots chart stuff - keeping things updated, care plans, etc, but I don't know anything about that yet.
You have to learn the machine - which is very intimidating at first. It's sort of complicated to set up at first- but once you learn it, it makes more sense. The company I work for (Fresenius) seems great about education. I spent my first week in classes, and I have two more weeks of classes coming up.
As I said, the nurses I work with really love their jobs. We have a really great group of people, and my boss is awesome. Everybody is very dedicated and attached to the patients. I'm told that with dialysis, you either hate it, or you love it. It's fast paced, but not like the hospital. You don't have to deal with other departments making your job harder (pharmacy, lab, etc) Admissions, discharges, procedures, etc. Geeze I hated dealing with that. I can deal with anything a patient has to dish out, but I can't stand all the other stuff that goes along with hospital nursing.