canisters are a bad idea because the create more nitrate than anything. if you going to use it take a piece of live rock and smash it into very small pieces and put that in some filter bags. never use pool filter sand, full of silicates and you will have algae growing out of the tank. carbon is fine it will help polish the water, and filter floss is fine too and shoud be the first thing the water touches. change that every 5th day to be safe. you can buy floss cheap in bulk packages and just cut it up to fit in your filter. if you dont change it regularly it will keep filling up with particulate mater and break down, decreasing the quality of your water over time. water changes must happen to keep the quality down. I would also highly recommend a skimmer of quality. this will also help remove crap from your water. if you dont buy one of these water changes become larger and more exspenisve.
IMO i would focus on getting a NICE skimmer rated for something maybe double your tank volume. this will help you more than anything. If your tank is large enough consider getting a sump as well so you can have the skimmer in the sump. doesnt really make it work better but it keeps it out of sight.
