I finished the last few steps in about 2 hours this morning... and then had problems.
The pipe up from the sump tank leaked a little, as did the drain pipe. And the pump wasn't pushing enough volume to overcome the drain holes in the stand pipe, so the growbed wasn't filling. I looked at the pump and decided it just wasn't big enough for the job. It's supposed to push enough water to cycle the entire system each hour, but it clearly wasn't up to the job and didn't have a volume control.
So I drove 30 minutes to the nearest open aquarium store, bought a 375 GPH pump with 6' head and a volume control, took a different route back to avoid some ugly traffic I'd seen on my way out, and decided on the way to ditch the sump-to-fishtank piping and go with tubing instead. I stopped at Home Depot and bought some kink-proof hose in the fountain section, and a half-circle bracket to fasten the end to the upper lip of the fishtank.
This pump is a HELL of a lot stronger. So strong, in fact, that it was exceeding my overflow pipe drain holes.
So I drilled twice as many.
I also glued the drain pipe, but it's still got a bit of a leak. I think I'll replace it (can't redo it since it's glued) and use some teflon tape this time.
Now that the pump is pushing enough water, I realized that my clay pellets only came up to the waterline. It's vital that they be above the high water mark so they don't grow algae. Luckily, I still had another 100 pounds of pellets I hadn't put into the growbed. So I dumped those in and it's perfect.
As soon as I recover from it all (and catch up on the housework I intended to finish today and the dinner I planned to cook on Saturday) I'll get the plants in there.