RDWC Troubles, Feedback Appreciated!

First time poster here. I've been reading on forums for over a decade but only have a few soil grows under my belt. It's been almost ten years since then and I'm finally able to have a legit set up. I have a lot of knowledge but very limited experience.

Anyway, started a RDWC system exactly two weeks ago and they are doing okay, but could be a lot better. Hoping to get some feedback on what can be improved. I've read and read, but can't pinpoint what my plants are struggling with. Here is some data on my grow:

1000w MH raised as high as possible (3'-8" from tops)
(4) 5 gallon dwc buckets connected to 18 gal controller/res.
Air Temps 75-80 F
Humidity 50-60%
Water temp 65-68 F
hydroton in 6" net pots
4.5 x 5.5 x 8 ft custom tent
400ppm + 150ppm starting tap water (starts at 7.8 ph)
GH flora 3 part with orca beneficial bacteria
~1000 gph air being pumped(1 stone/bucket, 4 stones in the res)
(4) blue dream clones

I acquired clones that were rooted in soil. The transplant went smooth but they showed signs of stress for the first week. Drooping, yellowing leaves, and some burning on the leaves. This can be seen on the lower growth in the pics.

After the first week roots started poking out of the pots and they perked up a lot. Root growth is exploding and they are definitely growing up top. The new growth looks a lot healthier, but still too yellow. The yellowing looks like magnesium deficiency, except it is not exclusive to lower leaves.

I'm not sure if my issues are related to nutrients, root damage, or light toxicity. I think it is probably a combination of things. I'm hesitant to lower the light or increase ppms if they are still stressed at all. What do you guys think might be the problem? Or am I just expecting too much for my first hydro grow? The last pic is the healthiest looking of the three.

Forgot to mention, PH has been 5.8-6.0

Got a couple questions for you. Why are you running the light so high and far away from the plants? Also, how come you are running the ppms so low?
I typically run lights as close to my plants as I can wothout burning them. I run MOST rooted clones at 1000 ppm and sometimes get to 1500 ppms in peak flowering. This dpesnt apply to long flowering sativas but most indicas and indica dominant hybrids can handle the higher nute levels. Also, I fluctuate my ph a bit from 5.2 to about 5.9. If I were going to try to keep it steady in hydro, it would be 5.3 I think those plants look starved to me.

I'd give them about 200ppm more food.

Okay, thanks guys.

Guess I'm just overthinking and being too conservative. Wasn't sure what counts as early veg or aggressive veg and was more concerned about over feeding than under. Had looked at all the deficiencies but hadn't thought about under feeding in general. As far as the light, I didn't want to overwhelm them coming in from flourecents and the bleaching looked like they might not have been handling the light to me.

I bumped ppms up to 700 last night and lowered the light about a foot. Will see how they do after a few days and probably bump it up again this weekend.

Let us know how they do. You replying and saying that made it all better or made it worse might help another grower down the line. Hope that fixes your issues. BTW, I veg with florescents and flower with a 1000 HPS all the time and never had an issue with bleaching. Only issue I had once was pushing the envelope and had light really close to plants and everything was great with a fan blowing right across the tops of the plants but when the fan failed, tops of plants got burned pretty quickly. General rule of thumb would be to put your hand under the light for a minute. If your hand gets too hot, so will the plants. If your hand is comfortable, so will your plants. I typically run my light about 18 inches above the tops and have a fan circulating air as well but if the fan fails, plants wont be harmed.

Will do. They showed MAJOR improvement after just 24 hours. Lots of growth and the new stems are much more green rather than reddish purple. Pretty sure you guys steered me in the right direction. I still see progressive yellowing so when I get a chance this week I plan to change out the res and add 1000ppm with a 3-2-1 ratio (grow-micro-bloom. Will post pics again after a few days. I may also do a foliar feeding tonight, still doing some research on it.

Btw, I'm no longer concerned about the light. Was just grasping at straws. I keep a thermometer at canopy height so I should be able to figure out an optimum height. Pretty sure I could do 18" without issues.

It's about time I give you guys an update.

After I raised the ppms I started having slime problems. Lost most of my roots over a week period trying to kill it. Ended up going with a tea and it cleared things up have been running beneficials since.

I'm' nearing harvest now. Things could be better but I'm happy considering the problems I've had. Just hit 8 weeks flower but I'' going to let them go for another week or two. I think the stress is causing them to finish up a little late. I've had some PH issues and was overfeeding for a while. I also have a couple tops too close to the light which are definitely getting stressed (was too late to train or top).

I'll just have to do better next time.