Last weekend the water tested too high in nitrites, and my growbed was clearly not going to be finished in the next day or two, so I purchased a 300 gph aquarium filter and hooked that up. Hopefully that'll keep the tilapia healthy enough until I finish everything. I've also cut down on food, though that's hard to do since they swarm to the surface when I'm there and gobble up the pellets when I feed.
This weekend I (with the help of a coworker/friend and her circular saw) finally got the legs onto the growbed. It required a lot more cross-bracing than I'd expected during my initial planning, and I wasn't going to skimp on that once I realized how wobbly it was, but that's taken care of and it feels very sturdy now. (I'll post pics later this week.) The bed is nearly perfectly level. It actually slants just slightly away from the incoming water and toward the drain.
I've once again pulled the fixtures out of the rain barrels and tried yet another method of silicone and attaching them. I'm giving them 48 hours to cure per manufacturer's directions, and then I'll pressure test again... except I just realized while typing this that it rained last night, and I left the barrels outside because it NEVER rains here! Oops. Sigh...
I've already purchased the hydroton, and it's waiting next to the greenhouse. On the bright side, the rain probably washed away some of the clay dust from them.
If the rain barrels pass the pressure test, I just need to decide what type of drain system I want to use, make/install it, and finish plumbing the overflow out of the tank into the growbed (I've already got the pipe from the bottom of the FT to the overflow hole). Everything else is done... I think... until I realize something else I've missed.
So the final decision to be made... what kind of drainage will I do? The GB has a huge hole already in it, with gaskets and stand pipe. But I don't need a drain hole that big. (Off the top of my head I think it's 3" diameter.)
- I could drill a small hole near the bottom of the stand pipe and use a timer for quick fill and slow drain.
- I could build a bell siphon, but with an outlet that large I don't even know what the specs would be for all the parts. I could figure it out, or maybe ask around. But bell siphons just seem so finicky to me.
- I could do an internal or external U-siphon. I'd still need a reducer, I think. And it has to be on the downflow of the pipe or it won't work. But I think that's probably the most fool proof.
- I could use a tube for a loop-siphon. Those also seem a little finicky and harder to keep clean. And I'd still need to reduce a ton before the tubing.
The fully braced leg:
The side view with both legs:
Side brackets attaching the growbed to the fishtank: