Kali Mist Nute Issues, DWC System

[RobsGreen]

Hi, I've been growing a couple kali mist plants for about 56 days from seed. There in a DWC tub and I'm using the Lucas formula for feeding, (General Hydroponics FloraBloom & FloraMicro) When I started I had the nute level way to high (500ppm @ .5 conv) and I burnt them up pretty bad, after that I changed the water and had it at 150ppm @ .5 for quite a while, just a few days ago I took it up to 200ppm and now its at 220. At this point it looks to me (very unexperienced) that they are nute deficient now, does that sound right? If so what do you think I should be doing at this point? I'm going to be cloning them this weekend and then switching to flowering in a week or so, I have no choice, I've been waiting as long as I can for them to get healthier. Here's a bunch of pics, any comments would be great. Oh yeah, I also can't keep the PH stable, some nights it will drop to 4.4 other nights it will go up to 6.2, I have no idea why. I try to adjust it to 5.6ph.



Plant #1: This one got burnt really bad, I've removed as many leaves as it has over time.


Plant #2: Didn't suffer from nute burn so bad, it didn't grow at first because of heat stress, almost died one night, but it also could have been because I kept the rockwool cube to damp at first, either way its nice and bushy.


Is that nute burn or nute deficiency?












This is one of the top leaves on #1.