Space itself. I believe there are other intelligent life forms out there and some of those happen to be close enough to communicate to each other/discover each other. We just hit the unlucky(or lucky) spot that we are simply too far away.

I used Jacks Hydroponic 5-12-26 Part A and part B. Idk if it’s my climate(10a) but it’s all I’ve had to use. I have also had no issues with multiple plants in the same tower. I’ve grown fruiting and leaf plants at the same time. I don’t use bloom nutrients. I’ve been doing this since ~2020. I found through trial/error that keeping ph at ~6 and my EC at ~2.5 everything just seemed to grow without issue lol. I always grow in season and don’t try to start lettuce in the middle of a hot summer for example.

These are lemon cucumbers and the classic marketmore 76

Bought. I looked into diy but honestly was too lazy lol. It’s a lettuce grow farm stand and has everything you need minus the plants themself. It has good spacing and blocks light inside the system to prevent algae growth. They sell seedlings but they are way to expensive now. I start my own with a simple led grow light and jiffy peat pellets+clay pebbles+fan