My gold fish pond is mostly completed, the gravity fed system is working so much better than my vacuum system in the big pond. BD drain is a cheap shower drain from the hardware store. We used a piece of plywood and some arts and crafts foam sheeting (it comes in different colors) this protected the EPDM liner and gave both the drain and the liner support so they could be hooked to geather with no leaks. I still have yet to cure the concrete antivortex dome I built, but this thread is not about all this stuff. Its about what come after it. THE FIVE GAL. BUCKET EXPERIMENT!!!!
I made the cone with 2 inch riged craft foam, much like the stuff used for floral design but in white. We figgured out the angle we wanted for the vortex and cut rings to sit inside the bucket. There was some shaping to get every thing just so and a squirt of expanding foam here and there to glue and fill in cracks. Next we tried out hand at fiberglassing. If repeated, the cone will be fiberglassed, but the plumbing will be installed with my new best friend UniSeal.
The bucket still needs some tweaking. In the picture the pass through from the vortex to the bioconverter has its elbow facing down and not up like in the design, this was due to the piece of junk pump not being able to keep up with the gravity fed system. It either pumped dry or overflowed. Still we have purged the bucket several times since installing the system.