sounds sweet man - great work putting it together, hope it works well for you.
here are a few things I've "reflected" on, now that this particular project is fresh in my mind...
as electrobes observed, a pump with considerable GPH was recommended. Much higher GPH than most any commerically produced canister filter is rated at ... this is because of the "inefficient" design of these "whole house" type filters ... they are designed to work with water pressure of 40 to 100 psi, which forces the water through all the bends, turns and what-not ... when using a simple aquarium pump with one of these filters, most of the pumps power is wasted on those same bends, turns and what-nots ... a commerical canister filter would be designed to eliminate as many "bottlenecks" as possible, to ensure a smooth and easy flow of water ... this lets them use a much smaller pump, and still maintain a good flow rate
the second thing about using one of these "whole house" filters is media capacity. with the 'strainer' tube in place, you can probably get 2 - maybe 2.5 cups of activated carbon into the cavity ... that's not a lot of media ... my fluval 404 (which cost around $90) can hold 2 liters of media (~8.5 cups) ... that's nearly 4 times the capacity, and only costs about 2 times as much (omnifilter + strong pump + fittings + hose = ~$50) ... I'm not saying the fluval is a great filter (it works fine for me), but if you look at the "value" of it, it is clearly a better choice than the diy method
finally... asthetics; i didn't used to care much about how my tanks looked, I was more interested in the mechanics and biology, than the decorative and asthetic appeal of the tank ... but now my tastes have changed ... to me having a large pump with some sort of sponge prefilter on it would look "out of place" in one of my tanks now ... I would try to hide it best I could, but it would be there still ... sure, you could setup an overflow to a sump and hide everything in the sump, but I've yet to figure out how to make an overflow 'silent' ... there is always noise, from a gurgling to a whoosing to a splashing ... my fluval: absolutlely silent ... even at full output ... plus, the intake strainer sits low in the back corner of the tank, hidden behind some anacharis, the outlet (which is connected to a spraybar) sits closer to the surface of the water, it was once a stark white pvc contraption that has now been adopted by algae and bacteria, and turned a good shade of brown ... with a little fox tail and anacharis draped over it, blowing in the current, it looks pretty cool ... the fluval sits in it's cakepan (to catch drips from maintainence) under the stand, quitely filtering away ... I can usually go for 2 months between cleanings ... it lets me know when it's time as the impeller starts chattering once enough gunk builds up in the impeller shaft well
these are just a couple 'o things to keep in mind for others looking to re-create this project
l8r,
glm