Okay guys, thought I'd update you on the progress so far... I've been experimenting on ways to keep the chamber cooler and I've settled on a way to run some coils of chilled water (40f) in the bottom that seems to keep the temps 10-15 degrees cooler than the surrounding air- even in direct sunlight. I also decided to put only (2) 3" netpots in for now so the roots have plenty of room to grow and let the fog have room to move around. I may add some sites later depending on how things go, but this'll be adequate for now. The netpots are around 100mm from the sidewalls, and about 170mm from eachother.
I was having a bit of a rough time figuring out how to install the cooling lines in the chamber, and have the chamber still hold water without leaking from the ports where the lines enter and exit. The problem was all the other holes in the box had threaded collars glued to both the inside and the outside walls except for these lower sidewall ones. I believe they lacked the inner threading so that the chamber would drain more thoroughly if they were used as drains. I wanted to make sure the box would hold water incase I wanted to use it as a reservoir during the veg stage so I could just recycle the nutes from there. After playing around enough I finally realized that the compression elbows from garden drip lines fit very tight into the threads, so I wrapped them with some of that "As seen on T.V. Magic plumbing tape" and screwed them in- which made a perfect watertight fit. I also found out half inch clear vinyl tubing fit into the dripline compression fittings without leaking. Yay... You can (barely) see (the red digital temp readout) of my chiller working hard on the lower right in this first shot and the castors which are installed on the chamber which makes it easy to move around and also raises it up so the drain holes are easier to run to a collection pan. Right now there is about 15 feet of 1/2" tubing coiled in the bottom recycling from the chiller. Once it's all figured out I will insulate the clear tubing outside the chamber with some foam sleeves.
Here is the rootscreen I made from a custom size screen kit and some 150 tpi silkscreen. I am thinking some NFT spreader mat might be a better choice eventually since I'm out in the hot sun (it'll hold a tad more water and give the roots a little more moisture to draw from if needed) but I already had the silkscreen leftover from my hydraulic chamber build and decided to use what I had. The screen will also serve to keep the roots separated from the cooling coils and act as a filter should I decide to recirculate the nutes during veg. It's sized to wedge down into the tapered chamber just an inch or so from the bottom, and I plan to silicone around the edge to keep any adventurous roots from getting underneath.
Here is the lid after I cut the netpot holes. I plan to have the one site in line with the nozzle to be at the farthest point so the mist has time to disperse and spread before squarely hitting it's rootball.
Here's the cutout piece shown to illustrate the chamber design and how it's filled with foam. The lid appears to only have one layer of foam, but the website states there are 3 plies in the rest of the chamber. I used a 3.5" holesaw to cutout the upper layer of the lid, and then cut my 3" holes in the bottom layer of plastic if the lid. This way I can drop the netpot all the way down in the chamber despite the thickness of the lid. I'm keeping the cutout pieces incase I ever want to glue and refoam so I can redo the lid however I may wish into a different configuration in the future if need be.
After cutting, there was foam exposed. I know firsthand how quickly the foam degrades in uv rays and sunlight, I also
worried it might eventually become waterlogged, so I applied a thin layer of white 2 part epoxy to seal it back up and protect it. I think it looks a little nicer this way too
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Here's the exciting part- the mist in action..! I put a black trash bag in there for contrast so the mist could be easier seen. When the lid is closed the haze hangs around for literally minutes. The real fun is going to be in finding the optimal height for the siphon tubes, air pressure and adjustments for the timer. The higher the air pressure, the more water is drawn in the nozzle, but also the higher the siphon height, the mist is less dense and in smaller droplets. I'll have to find the optimal siphon height and air pressure that creates a mist conducive to plant growth and root hairs, and then hopefully all I'll have to do after that is adjust the timings based on the plant needs and stage of growth.
