Let me answer the question one at a time. Charles, fill the reactor half way. It will hold 200ML's. If you can, use RO/DI water to gently flush out the fines. You will see dark brown water exit the reactor at first, then it will clear up. You can now connect it to a small pump, I like the Hydor L25. Start off with a very slow trickle. After a few weeks you can then kick up the flow a bit, just until you see the ROWAphos start to move on the surface. If you start out slow, you will have no problems. I hope you are testing for Phosphates so you can see the change.
Brian, I have tested carbon and different foods, all dry and they all produce phosphate readings. Some more then others. Remember, phosphate is a inorganic salt and is present in most things we put into our aquariums.
I agree on the algae filtration method, the EcoWheel comes to mind, but you need a very large area to grow algae for it to do any good. That is why all the early algae turf scrubbers never made it big, because they had to be so big to work. That is one of the main reasons I see lots of aquariums that have become over grown with algae and have very low Nitrate and Phosphate levels. They already have a algae filter. It's covering the aquarium.