Ok, yellowing leaves, but my PH and PPM levels are untouched

Hello everyone, this is my first DWC setup! i have 12 gallon totes (that ive atempted to light proof, going to buckle down and get black ones soon) and im having a bit of begininers trouble.

As of right now theres 6 plants in 3' netpots in a 12 gallon tote. my ph level i keep between 5.7-6.1 but always aim for 5.7 myself. i have NOT added any nutes to the water as the plants are under 6 inches tall and still devloping a roots system and i use tap water that has a ppm of about 387. My leaves on some plants are yellowing and i think im going to lose at least 3 of my 12 so im ready for the loss and the lesson lol.

i havent used any nutes mainly cause i was under the impression i needed NOT too while they are still young. i have no fungus or algea growing so im asssuming my issue here is nutes of some sort since i have ZERO in my res. whats yellowing leaves a possible sign of? thanks everyone

They are hungry, give a 1/4 strength dose of nutes and work from there.

ok, brought the PPMs up from 368 to 390ppm and will work from there. thank you

~ 400 ppm sounds like very shitty water. Check out the post Al b Fuct. He is a very experienced grower and can tell you if your water is bad. personally i am OCD about my plants and they get nothing but r/o water, not always needed.

Dirty Jersey: yellowing can be a lot of things but it sounds a lot like nutes and that's where I'd check first. I wish that there was an easier way, but I suggest the following:
1. Read: SeeMoreBud’s book, “MARIJUANA BUDS FOR LESS GROW 8 OZ. OF BUDS FOR LESS THAN $100.”
2. Read: Jorge Cervantes’s book, “MARIJUANA HORTICULTURE THE INDOOR/OUTDOOR MEDICAL GROWER’S BIBLE.”
3. Read: Ed Rosenthal’s, “MARIJUANA GROWER’S HANDBOOK.”
4. You’ll want to read: Mc Carthy’s book, “GROWING MARIJUANA.”
5. You’ll also want to subscribe to, “HIGH TIMES,” magazine. Each issue is chocked full of useful information. .” All these resources are very well written, well illustrated and packed with information that will answer most of your questions before you know to ask them. This will save you and your plants a lot of anxiety. I hope this helps. HSA