this is the second version of this filter i have tried. the first one did not turn out well at all.
the supplies. pretend the jar doesn't have a hole in it. there is a jar, a drill with a spade bit, three kinds of hose barbs. two of them are 1/2" and one is 5/8" i believe, possibly 3/4. the two 1/2" are screw-in. one of them is 1/2" to 1/2" and the other is 1/2" to 5/8" the third is female, so it will screw onto the threads of the 1/2" to 5/8" male hose barb. they didn't quite fit together right, the threads were spaced wrong, but a little sealent fixed the gap. i also have some hoses that fit on the barbs, an exacto knife, and scilicone sealent, and of course the pump or powerhead.
first step. mark your holes. one should be low on the side of the jar, the other in the lid. use a spade bit the size of the threads of your two male hose barbs. the wider one should be on the top. i did not have a spade bit quite large enough, so i had to use the exacto knife to widen the holes just a little bit. also, spade bits do not do well drilling all the way through plastic, but they do a great job of scoring the hole the right size so you can come in behind it with the exacto knife and clean up the hole.
next, fit the male and female hose barbs together so the larger one is on the inside of the cap, and the smaller is on the outside. (the size actually isn't important at all, it just so happened that the outflow of my powerhead fit better into the 5/8" tubing, which fit onto the 5/8" hose barb. choose whatever sized hose barbs and tubing will fit your pump.)
it should look like that once you've got all three hose barbs attached.
there is the pump attached with a small bit of tubing to the hose barbs. one major, MAJOR change though is to always have the outflow in the lid. the water should come in through the bottom, and be pushed out by the pump through the lid. so after some trial and error, i switched it around so the outflow of the pump was stuck in the tubing instead of the intake.
the last part would be to make a hole for the cord. i did cut the powerhead cord. i use an 1/8" drill bit to make three small holes as close together as possible, then used the exacto knife to clean it up and fit the cord through, then coated it with sealent.
for sealing everything else, the female hose barb in the top comes in two pieces. one is the barb itself, one is the female threads that it fits into. mine did not fit together quite right, so i put a layer of scilicone between them to fill the gap. i sealed on the inside and outside of all the holes i made.
once i switched the powerhead around so it was pushing the water out the top, rather than trying to push it out the bottom, the canister worked perfectly. fill it with your media and cap the end of the hoses with some mesh and you're ready to go.