https://horticulturelightinggroup.com/products/hlg-550
Get 3 of those if you have $4k. One for the 5x5 tent, two for the 9x9 on your light movers to replace your HPS. Get some other supplemental side lighting for the 9x9 with the remaining thousand.
Regular H series is SMD pins. HW (i.e. wired) series has cables which are not compatible with the rapid boards so far as I know. I've used HW drivers in a couple bike lights and have some H's sitting around because I initially ordered the wrong ones.
So you're giving them so much light they used more nutrients than your setup previously pulled? Sounds like you were running sub-par lighting prior and your plants weren't reaching their full potential. Pretty cool!
How to collect indigenous microbes from your backyard forest: http://naturalfarminghawaii.net/2015/03/indigenous-micro-organisms-march-2015-meeting/
Just adding soil probably won't be beneficial. Make the concoction I linked using the rootbase of that same cedar tree, now that'll be beneficial.
No, once mycorrhizal colonies are established there is no reason to add more inoculants. There is a fundamental misunderstanding of how this stuff works in growing communities that is for some reason very well understood even in the normal hobbyist gardening world. Mycorrhizae are a big part of...