I have a fluval 404 and right now i'm not sure what to put in the the 4 media slots. Right now i have the ceramic rings and activated carbon. I want to add some other stuff to control everything else that might be happening in the goldfish tank. thanks for any advice!

I would add a mechanical filter pad/fuzz/floss, whatever your filter takes, and use more bio media in the other, you can never have too much of that stuff

i have ceramic rings, bio-stars and seachem matrix in my rena filstar XP3 canister.

I agree you dont want to add things like ammonia chips unless your tap water has it and your using that water. Adding things like that to the filter will just cause more trouble later down the road

No ammonia removing things? what kind of problems can it cause?

Well your tank needs ammonia to a point to keep it cycled. If you look at the chart of a cycle you will see that the tank will go to ammonia, then nitrites then to nitrates, so the natural amount of ammonia is needed for the tank. If you use this stuff with a tank that doestn have ammonia in the tap water you could be depriving the tank of the natrual amounts of it with the fish

oh...i see. I was thinking of adding some things that would eliminate or limit the growth of algae

Phosorb is a good product for that. Also a Bristle nose pleco would help you out too

Depending on your KH, you may want to put in broken coral to help with pH buffering. (If you need it).

From my recent bad experience, it's easier to put coral in right at the start, before you fill the cannister with water.

I've got a really old and crusty cannister that doesn't self prime, it only has a topping up hole that doesn't work!! Hopefully you don't have that prob.

Slugger