Yeah, the rocks are clean and the rockwool is exposed to the light. It's also sitting down in the water by about 1/8 inch or so. The root was barely extending out the bottom, so I figured it's be OK to do for the first batch of solution then lower the level when I change it the first time.
How would I transplant it to a new cube without damaging it? It's only six inches or so tall, and I'm sure still fragile as all get out. The new rockwool, I can cut a slit into to insert it, but how would I get it out of the current cube? Is it still young enough to only have one root shoot?
As for it being exposed to the sun, this is an indoor grow. After reading a few other posts here, it seems I may not be able to do that with tomatoes. I'm not sure I want to spend the money on an
hps lighting system and ventilation to cool it, so if it's not too late in the season (which I'm afraid it just may be) I may move this setup outside and build something for lettuce and kale inside. The indoor tomatoes were just an idea for year-round fresh tomatoes. Maybe that's not something that's cost effective for only a few plants.