is this rust? Or over nute?

Ok, so in the pics you can see the plant that's been affected most. It's a lowryder and is in a DWC hydro system. The first true leaves have completely yellowed and remind me of the dying bottom leaves of recently rooted clones.

I'm thinking that it's either rust, or over feeding? I was up to about 7.5 mL of foxfarm per gallon, but I backed off to about 5 mL when I saw this problem, perhaps I should go even lower?

They're under a 400 watt HPS light right now. I'd appreciate a couple suggestions before changing my reservoir. I'd especially appreciate input from Latewood, Turtle420, and the Student :D

what is your ph of your water?looks like an n def.

no pro here, but id say there too young for nutes

ph is 5.8-6.0 controlled by an automatic doser. The nute solution is very diluted, so it should be fine - they are in hydro.

The pH is kind of high -- needs to be between 5.0 - 5.5 otherwise you'll get lock outs -- especially manganese.

Try bringing it down to ~5.2, and ease up on the feeding. They seriously don't need very much at all at that age.

Woah, that's way too low. 5.8 is the magic number.

So, where in the plan does the plant get to soak up some manganese? Now I may be mistaken, but 5.8 is just a little high for uptake -- a little drifting is necessary now and again.

To me it looks like a manganese lock-out -- blotchy and chlorotic.

I've always been told 5.8, and when you look at the uptake graphs, you get the best balance of uptake of all the nutrients.

So for now, I emptied and refilled the res. I currently have about a 1/3 strength thrive alive solution, 1/8th strength foxfarm solution, and a little under half strength earth juice catalyst. Hopefully this will fix the problems, they probably are a bit young for even the half strength nutrient solutions. I'll try to remember to post pics in a couple days.

5.8 is good, but it needs to drift a little lower on occasion to get everything. I use that same graph in the FAQs, but I also use another. Both state a pH between 5.0 and 5.6 is best for manganese uptake.

Keep an eye on them for the next couple of days and watch the new growth for any signs.

I'll see what happens. Haven't had issues with the ph at 5.8 in previous grows. We'll see what happens.

Ok, the bigger two seem to be pulling through pretty well, while the small one is pulling along and I think might survive. The last picture is the smaller one. I think it'll pull through with this. They just obviously need only a very weak solution.

Sorry, took the pics kinda quickly and the hps was on, but they give an idea of how they're doing.