This week I waited for parts. Well a bit more than that, but it felt like I was always waiting! The tomato seedlings were transplanted on to the plant topper rockwool cubes. These will eventually go in the the “slab” which is a large block of rockwool that supports 3 plants. For now, all the cubes are just in one tray, each with their own dripper. It’s hard to find good information about this stage of propagation, most experiments (and large growers) seem to order them from a transplant supplier. I just don’t have the connections for that. According to the best information I can find I’m giving them ½ concentrated fertigation and irrigating about once a day in the morning to about 80-90% saturation. The plants are small so they are not transpiring out a lot of water yet… But the drain (runoff from watering) is about the same EC (electrical conductivity, indicator of amount of nutrients in the water) as the fertigation water so I think it’s ok.
I got the next iteration of my slab weighing tray working using pneumatic cylinders. Mechanically it seems fine. Electrically, I had tons of trouble with the HX711 load cell ADC chips. I had to solder up like 6 to find 2 that worked. Plus I had tons of trouble with poor connections. I finally went and learned how to make a custom PCB (printed circuit board) to mount everything for the load cells. Those are on order (next week delivery?) and should make it much easier. I also ordered more expensive HX711 chips from a Canadian supplier so hopefully those will be more reliable.
But that’s not all! Activating the pneumatic solenoid valve with the relays I have restarts the arduino Mega micro-controller. So I ordered a new relay board that has optocouplers. This uses light inside a chip so that the controls (arduino Mega) and power being switched (solenoid) are electrically isolated. This problem also happens occasionally when the pump for misting turns on. I sure hope that does the trick, otherwise I’m not sure what to do. Faraday cage around the Mega?
The misting system worked to keep temperatures below 30c on some hot sunny days this week, but I did have trouble with the mister heads clogging up. I put in a 1 micron prefilter, but since then it’s been cool enough not to need the misting.
Sun Aquasystems 