Just skimmed your grow thread, looks like you have multiple issues going on. Either use bennies, or a sterilizer, don't use both or you'll just be fighting yourself. Bennies take awhile to get established, if you go sterile, you need to make sure it stays sterile, 24/7.
You were WAYYY over feeding them initially. You shouldn't have added any nutes until they had 2-3 true leaf sets, seedlings just need water, maybe a little calmag if on RO, like 0.1EC. In those first couple weeks pics, the plants looked cooked: crispy, brown, twisting leaves.
I think you need to get your nutes dialed in a little better. Add calmag to RO first get 0.2-0.3EC, then add nutrients to get the total EC you're looking for. Those plants should be around 0.6-0.8 (420-560ppm@ .7 CF) EC total. Never run plain water in hydro,
except to leech the media, which would be a wash, dump and refill with fresh nutes. Always keep a low EC, like 0.1-0.2EC. Plain water can stop nutrient transfer, both in and out of the plant, it'll process better with that lower EC. I'd try running around 0.3-0.4EC of your base with a doubled hydroguard application @1ml/L for a few days. It's always easier to add a little more than take it away, plants will do better being slightly under fed than slightly over fed. Also, mix around 1/2L ea of water and hydroguard@1ml/L and pour it through your grow medium, do this a couple times over a couple weeks, it'll get a bennie herd going in the media. If you go sterile, don't bother with the hydroguard, you'll just kill it off. Too much nutes, or adding bennies then sterilizer which kills them, provide a buffet for bacteria to thrive on.
Always mix nutes, add to res, then adjust the total res's PH. Never adjust nutes then add to res and then try to readjust the whole thing. You'll just keep chasing PH.
These are all things that'll get better with experience.