http://www.zeovit.com
http://www.captiveoceans.com
http://www.aquariumobsessed.com
I have bought supplies from both places but I would recommend Aquarium Obsessed. They are the Canadian Distributor for zeo. I have temporarily discontinued use of zeo as I have had issues trying to get a zeo reactor from Captive Oceans despite having paid for it nearly 8 months ago. Will at Aquarium Obsessed is great to deal with and from all accounts also an outstanding tank builder.