Yep umm its not a huge pond so as long as the bio load is not enormous you would probably be ok with the 5 gal bucket, but as everyone says bigger is always better. The idea of putting the post scrubbies/filter pads at the very top and bottom is almost more for keeping the actual bio media clean so it doesn't get super gunky, than it is for cleaning the actual water. The swirl filter will be your main source of mech filter while the pots scrubbies/filter pad will almost be like protection for the bio media. Also the ceramic rings are actually for more of mechanical filtration then they are for bio, but they do both. The sachem pond matrix material is purely for bio and its basiclly sinsterned glass, and you dont have to get that brand. There is debat that the surface area of the sinsterned glass (which is much bigger than any other media) is most NOT usable by bacteria becuase the holes are smaller than the bacteria and it can't grow in them. So some people like it, others don't it just depends and I am not sure that there are any studies proving or disproving this so it just might be people speculating.