Is there anything else you have to buy with the controller or is this all you need and how does the controller accualy control the ph, as in what does it control it with? Here is the one I was looking at:
http://www.marinedepot.com/American_Marine_Pinpoint_pH_Controller_Single_Item_Monitors_Controllers_for_Saltwater_Aquariums-Pinpoint_Monitors-AM1311-FITEMOID-vi.html
this is just a controller (and a probe), so you still need pumps, lines, solution, etc. the controller is just the 'brain'.
I have found very little information about PH Controllers in general, so if there is any interest, maybe we can improve on this?
I have the Pinpoint PH Controller. I am happy with it and to me it was worth the $200 investment for my bloom res; invaluable for when I am gone a few days or more, and otherwise just a great time-saver. This model features adjustment in both directions, which is pretty convenient.
I also have a Reef Fanatic PH Controller and I am also happy with this $150 investment. It only controls in one direction.
Note that despite the obvious notion of convenience which comes with controllers, setting one up requires patience and work to get the system tuned and functioning correctly. A little mistake can turn into a big problem in no time here. I managed to survive a few bumps in the road myself, but I am at the point where I just have to cal the probes periodically and all is well. I simply check on the numbers from time to time, but I do need to remember to disable the controller during res changes, doh!
I enjoy growing, but it was starting to take over my life, so the controllers are working out quite nicely.
Hope this helps.