After three cracked aquariums, I think I've got a working bell siphon design. The difficult part was, well... all of it really. Actually the research and design were pretty simple after running across Affnan's website. My design (shown below) is a recycled bottle variant. I had to refine my glass cutting skills a bit, and went through a number of practice bottles along the way, but think I've got the technique down now. Just need to drink a couple more bottles of wine...


The bulkead I had so easily envisioned was surprisingly difficult to source. I probably spent $20 in plumbing fittings trying to find a workable combination, then over tightened it and cracked the bottom. Then I bumped the mounted siphon in a second tank, and cracked that one. Then sliding a third tank across the top of my sump, ran the downspout into a partition (which I've trimmed down to prevent this going forward). I've worked out a repair method for cracked aquariums using clear epoxy. Hopefully, I've also learned to be more careful! Here's a little video I made of the workings thus far:

I've made a push to get the whole system going by next weekend, which in addition to some plumbing involved a lot of expanded clay ball washing last weekend before I had to leave on this week's business trip. I wasn't confident enough in my cutoff valves and pump flow to leave the system cycling while on my trip. Right now the tank is occupied by a couple of goldfish and some ghost shrimp, and some water hyacinths (see below) that I am using to detoxify the system, and provide shelter and nesting for my feeder fish. I'm debating about how many hyacinths to keep, once I have the grow beds hooked up and planted. I'd also introduced some water lettuce from the same source, but most of it rottted.