Turning HOB filter into fuge.

As i am not totally surprised, my LFS dude when i set up my system had me a get an Aquaclear 50 for my phospate/nitrate media. after reading on here for a while, i wanted your take on weather i should stick with the media i have in the filter or swap out the carbon and sponge for a fuge with LR/cheato. any suggestions are much appreciated !
would that small of an area be an ok place to culture pods? My reason for this tank is me falling in love with a mandarin. I know they require a mature system, and he will not be added until atleast 7-8 months after my cycle is complete. I want to be able to give him plunty of food and was considering making a pod culture. maybe i could kill two birds with one stone?
I'm sorry to say, but with a tank your size, a mandarin would go hungry from eating alk the pods quickly...but what your could do is find a mandarin that eats frozen foods and pellets. That way he'll have a great chance of survival.