Trick to not get "junk" in the tank with a Canister is to pull out the intake/return the second you unplug it so it doesn't "reverse syphon" back into the tank. If you pull it out as soon as it stops then air will get in the tubes and prevent that junk from happening. Always replace your media monthly, rinse or replace the filter pad at least weekly, and also if you use Live Rock rubble take all that out and swish it around in a bucket of saltwater you take out from a water change to clean out the rock rubble and remove any built up deitrus. Sounds complicated but it really isn't that bad/hard to do once you do it a few times. As for Macro Algae in a canister, sorry, can't think of anyway to do that one unless you know how to put a light in it for the Macro to grow.
