a really simple but, pretty bio--I use it in my goldie pond---I do have a bd and a gravity fed machanical filter--so no big stuff gets to the bio to clog it up....the pump sits inside of the machanical filter and then you can take a flower pot without holes in the bottom full of lava rock with the hose coming from the pump into the bottom of the flower pot so that the water goes up thru the lava rock and then either set it up on a table in the middle of the pond or next to the pond tilted slightly so it empties back into the pond...toss a bit of upright and any creeping plant bareroot(I used dwarf sweetflag and creeping jenny) at the top so it looks like a pot full of plants--It looks really pretty once its all filled in plus the plants will act as a filter too..I would put a check valve somewhere in the tubing so that when the electric goes out-then it won't siphon water out of your pot...or if you want to do a trickle tower kind of bio filter then take a basket of lava rock sit in the middle of the pond on a table and hook the pump hose to a piece of pvc pipe that is capped on the end with a whole lot of holes drilled in it(this type requires cleaning to keep the holes open) so that the water showers over the lava rock and back into the pond....you can also put some kind of creeping plant bareroot in the top of the basket...
Lawanna
this is a pic of it when I first put it in-now this is a 1,000 gallon pond-so you could use a bit smaller
pot on your 300 gallon...
and the pot filled in with plants-
