Never being one to leave well enough alone, I ran across this link: http://www.instructables.com/id/Hydroponic_Food_Factory/ and decided to wade in feet first. Literally. Never tried hydroponics before so there he goes.
I started off with PVC black pipe, 6 4 ft lengths. I picked up a dozen end caps at the same time.
After a little bit of eyeballin', I allowed a few inches for tubing and came up with 42" lengths.
tubes
A little more of the metric eyeball and it looked like the little planters I picked up at the dollar store would fit down into the pipe about halfway so I jammed one into the end of a pipe and traced a circle with a Sharpee, then cut it down with a box knife.
mark planter
I traced the planter pattern onto a coffee can lid and cut out the circle. Then I trimmed the outside of the lid so it would lie flat when I bent it.
trace
I slipped the ring over a planter to make sure it was a good fit.
pattern fit
I glued the end caps on a pair of pipes and set them up with 6 of the planters and nudged them around until they were staggered and fairly even. The measurements worked out to 6, 18, and 30 inches.
layout
Black pipe has a convenient strip of text painted down one side, so I marked the ring stencil on opposite sides and lined it up in the pipe, then traced the pattern on all the pipes.
trace pipe
I drilled 3/8" holes in each pattern trace so I could get the jigsaw blade in from different angles and started cutting. I used a die grinder to clean up the edges and do some final fitting on each hole.
start cutting
Round pipe will roll, so I made some feet for it. I sliced off 6 3" pieces of pipe, cut those in half and used a Tek screw to hold them in place while I slopped PVC glue in the crevices.
screwed and glued
I tossed 3 tubes into the greenhouse to check the fit and get an idea of what it was going to look like.
check fit
After doing all the cutting, grinding, gluing and screwin' around with the dog, I drilled the end caps. One end down low for the drain side and one end in the center for the supply. If I were to do this again the supply would be closer to the top, but wtf. I started cutting hose and plumbing it all together. the left/right zigzag is due to the hose's tendency to pinch and bind so I gave it plenty of room for gentle curves.
left plumbing
right plumbing
I put a 560GPH pond pump into the supply bucket and added a diverter valve to regulate the flow.
I ran the outlet out of the bucket to a T fitting so I could supply both top tubes.
pump and tee diverter
I held my breath and applied water. The results were less than spectacular to say the least.
Some pipes were overflowing, some weren't keeping enough water to wet a whistle. Hm. I took a break, started thinking about fluid dynamics and where I could have possibly gone wrong.
For starters, there was too much angle on each tube so I made another set of feets for all the tubes. Somewhere along that path I realized they didn't need to sit so high, so I whipped out the heat gun, mushed em down and set some weight on them as they cooled. Go ahead, ask me what's a brick meta for.
flatten feet
Part of my problem was unequal head pressure going to the top tubes. I pulled both those hoses and trimmed them to equal lengths. That solved the low flow problem in one circuit. I applied water again and had the overflow problem again. Hm.... one drain line was almost 4 ft longer than other and that was causing the overflow problem. That meant both drains needed to be the same length, but that presented another problem. There was a drain coming out of each side of the greenhouse, so my reservoir needed to be in 2 places at once or in the center. I decided on 2 places at once.
I took another trip to the hardware store and came back with threaded nipples, reducers and fat rubber washers. And 6 feet of 1 1/2 inch tubing.
cut the bucket
aux bucket
I ran the fat hose behind the greenhouse and it seems to be equalizing the reservoir level and the overflow has stopped!
replumbed
So now it sits out there humming along happily. Each tube has a couple inches of water and everything is flowing as planned. Whew.
This project took a week, but that was just spending an hour or so on it every day. I'm gonna let it run overnight and we'll know in the morning if it's gonna be a workable system. If it is, I'm moving on to part 3 of this project in the next day or two.