Any pet store around Vancouver should sell them including Walmart. The Magnum 350 has a filter that is desingned for use with diatomatious earth, the magnum is or used to be sold through Walmart under their brand name so you'll have to look it up to see a picture of it. They do an excellent job of polishing the water, I'd remove as much of the crud as you can before hand or they will plug up really really fast. Once you've used it you have to rinse it out extremely well but they work great.

Doug