OK all caught up, looks awesome in here Growlow! It's a bummer about the GO nutes mess while you were away, and about the early high temps but at least that's all under control now. I really enjoyed your video lol and not just because of your sexy accent
I've never even heard of doing a hybrid of soil growing in DWC hydro, but then I'm ignorant about all things hydro, very fascinating actually.
About the UVB effects on microorganisms I might have a sliver of knowledge; ultraviolet radiation at certain frequencies/wavelengths (This I've copy/pasted: Ultraviolet light is part of the light spectrum, which is classified into three wavelength ranges:
- UV-C, from 100 nanometers (nm) to 280 nm
- UV-B, from 280 nm to 315 nm
- UV-A, from 315 nm to 400 nm) is germicidal. UVC in particular shows the highest germicidal effects. Why humans experience sunburns is because of UVB in particular, a longer wavelength although the process is similar for microbial organisms' reactions to UVC. Ultraviolet Germicidal Irradiation (UVGI, once again mostly confined to UVC) doesn't necessarily kill microbes, but it does prevent growth and reproduction by breaking down bonds at the molecular level with a mutagenic effect, ie, it deactivates the DNA at a cellular level.
This is good if you want to, say, disinfect water from a dirty pond, but not good if you are exposing beneficial microbes to the light. You're using a UVB light, so I actually think it's safe to say you aren't going to kill your microbial activity, especially since it can't penetrate past your sand layer, but I'd still only run it 2 hours a day on your plants.
Hope this helps! Beautiful harvest, I think its safe to say you know your stuff!
P.S. just a warning though I'm sure you already know, don't ever look directly at your UVB light and make sure your skin is covered when near it, it really can damage your skin cells, high levels of exposure can even lead to cancer.