The largest of the four has been getting Mega Crop, and it's needing a higher dose than the rest obviously. It was the healthiest and largest before I started feeding the Mega Crop so I don't want to draw that conclusion early - but that's why both Mega Crop and Maxibloom are listed, they're not being used together.
Grow-Sil is a soluble silica product made from rice hull.
@grower_not_shower - I did. The strips are Bridgelux EB Gen2 3500k 22" models that I got from Digikey. I'm running them at about 700ma via an HLG-320h-20A. The strips are all mounted on 1x1x 1/16th aluminum square tubing.@CovikLaFlaire - If you look near the bottom of the left wall you'll see I've cut out a hole about the same size as a standard 14x25x1 furnace filter. I made a small channel for a filter to slot into on the other side so I get a good seal. That size filter fit between the studs in the wall and I can get it cheaply anywhere.