| Hello Ron, and welcome to FishTankForums!
Biological filtration is best established within the substrate of the aquarium, but it can also be supplemented with bio-filter media. This type of media can be either a part of the filtration system, or simply located in a fine mesh bag placed in a high-flow section of the aquarium itself.
How old is the tank, and how much substrate (sand/gravel) do you currently have in it?
Also, how often do you change out the cann. filter media?
Cannister filters are extremely useful and the one you have is probably sufficient enough for your needs. The glory part about cann filters is that you can use any type of filter media in them, you are not relegated to only one type. You can run the AC/Foam media for a month then swap it out for with a biological filter bag, then rotate back to the AC/F media again, or if you need to target certain nutrients in the tank you can use specialized filters such as Nitra-Zorb to remove excess nitrates, or Phos-Ban to remove unwanted phosphates.
In order for us to give you a more personalized answer to clean up your tank you might want to fill us in on your current tank parameters:
Temp
pH
KH
GH
Ammonia
Nitrite
Nitrate
Lighting period (photoperiod) in use
how often do you do water changes
etc.
etc.
Good to have you aboard!
-Aaron
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"The only thing that happens fast in saltwater tanks is failure."
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