I received a aquamaster 6000 (HOB) with the tank I recently purchased. The problem I have encountered is that he only gave me 3 of the 4 cartriges...lol. Instead of going out and buying the fourth one I figured that I would just take them out and replace with my own media. Has anyone used this HOB, if so what type of media have you placed in it. I was thinking about using scrubbies and then biomax for the upper half but after some reading I may switch to the ac 110 foam/sponge for the bottom half of the filter. Does this sound like the right plan or what would you suggest?