New grower

okay so we're still in business. Looks like we're getting steady growth now. I'm definitely not overwatering them now, and hopefully not underwatering. Also I did my first LST on one of them (pictured). Hopefully I'm not jumping into that too soon. I read you want to make sure to do it when the branches are still limber. It seems to be working ok. After watering them a couple days ago, I saw a fungus gnat lurking around so I popped some sticky traps but didn't catch anything except those tiny jumping beans. edit: welp, sadly it looks like I still haven't got a handle on whatever is slowing the growth of my plants and turning them yellow. The tips on some leaves look burnt so maybe nutrient burn? I haven't added any nutrients, only what's already in FFOF. The only thing I can think of is that my PH is still off. I don't have a PH reader yet, so I'm using PH drops to test. Also I've been using mostly distilled water to get the PH down, so maybe that's causing the problem. I wish I could get back to week 5 level growth. That was the healthiest I've seen these plants =[