Experience with Fluidized Bed Filter capacity, Grow out tank, Lifegard FB 300

[Manx]

I have some Lifegard aquatics FB 300 filters. (3 lbs sand)

Does anyone have experience about how many 4" (ca 8-10 cm) Discus I can grow out in a 50g tank with this filter connected?

I ask about the bacterial capacity of filter, not how many fish I can have in a 50 g tank.


Thanks,