Check out other places. I got mines from MD for ~11 bucks. I use mines as a ATO and the flow slows down after a while (just RO/DI water, no Kalk) to a steady rate. To increase flow, I unplug the silicon tube going to it for a few seconds and then plug it back in. Flow increases for a while again til it settles down. I haven't had time to look into it or run vinegar thru it yet.