Confirming this looks like overwatering. I’m having a horrible time getting out of the seedling phase in my new system (upgraded from flood&drain to RDWC). Same thing every time… plants start yellowing, drooping, and nosediving. What a noob.
Ph 5.8
Temp 70’s
rH 60%
RO water at 68 degrees
No nutes
RDWC with top feed system (1 min every 1 hr)
Thank you!
Is that one of those damn Jiffy pods that the seedlings is in? If so it maybe too much watering at 1 minute per hour. It is a challenge to start a seedling in that clay pebbles. I would water by hand a small amount on the roots about 2-4 times a day, until more growth is established. Using a mild nutrient solution for veg that includes micronutrients.
Most start hydroponic seedlings in rock wool, but I prefer the Root Riot Plugs, as they work in soil, coco, and hydroponics. They are more spongy than one would think, and doesn’t hold excess water.
Howdy
I always give nutes in hydro.
Start off low and slowly increase as plant grows.
Rapid Rooter. I backed off the top-feed schedule a bit. Thank you.
Thanks Hash. I’ll bump it up to maybe 150-200?
Howdy
I usually start off between 0.4 to 0.6 EC
Running seedlings in hydro can definitely have its challenges. I use rock wool and a germ tray and dome the 1st several days to get a nice long tap root then transplant to the net cup and hydroton. I also too feed the cup every other day or so just enough to wet the roots. Once I have several tiny roots showing I turn the system on. Make sure your net cup is 2” above the nutrient solution and isn’t saturating the net cup, you may need to cycle the pump. Calling in a great hydro Grow Bro. @Retiredoldguy any words of wisdom 
thanks for the tag @OGIncognito …I used to do exactly what you wrote for my seedlings but currently I go straight from soaked seed to my rockwool cube and into my tote with seedling nutrients and having good success with sprouting…
Thank you both.
I’m still not sure whats going on. They’re starting to look crispy this morning after backing off the top feed schedule. I added some calmag, 3-part and Silica.
I’m n my experience they looked over watered
I tend to agree, but when I compensate for overwatering the plants don’t improve. This is my third try and seedlings keep dying the same way; yellowing/discoloration, drooping, crispy, dead. More water, less water, doesn’t seem to matter.
Seedlings are also stretching a bit even though the MQ-610 is reading 200 to 300 PPFD. I’ve tried varying distances and power settings with the EVO3 LED. Lower power at 24" or a little higher at 40".
How embarrassing. Numerous successful F&D grows from seed to harvest and now I can’t get even get out of the seedling stage. So weird.
Maybe the water level in the bucket is high? It is touching the netpots, but the Rapid Rooters are sitting in dry hydroton a good two inches above the bubblies.
I start my seedlings even closer, and I use rockwool cubes. I use 1.5" cubes, but sometimes I use only 1/4 of that. The cube needs to start drying out about the time the roots reach the water level an inch or 2 below the cube. The bubbles moisten the hydroton layer between the water level and the cube for the roots to seek out. If the cube keeps getting wetter after sowing, then I lower the air volume or water level or both.
As the roots grow, the water level is slowly lowered over a few days along with the root growth to the desired level the water will run at (level with the netpot, 2" below it, whatever). By the time the water level is lowered to its permanent level, the roots should be well below that level, and deep into the water.
I never top feed. I learned from ebb and flow to never get the top of the hydroton repeatedly wet. It builds up salt and algae.
Oh, and by the time the cotyledons start opening, there should be nutes in the water, generally something like 25-50% strength, depending on strain.
Maximum thanks, Bub.
I stopped top feeding and lowered the water level. The “drip” lines may have been soaking the bottom of the Rapid Rooters…
Also, clearly not enough nutrients. I’m at 0.3 EC and will slowly increase.
my seedling nutes is 300ppm …some seeds just don’t make it unfortunately
Can you post some root pics Grow Bro? The net cup generally is 2” above the nutrient solution
Mixed results after lowering the water level, ending top feed, and boosting nutrients to 0.6 EC (start of week 3). One plant is drooping less while the other is drooping more. New growth is greening up a bit, but it doesn’t seem like the problem has been address.
Hard to imagine they’re still overwatered.
Cool, it will take a bit of time for some of the root mast to establish outside of the rooting pod. I used to use Jiffy Pods and remove the nets, and rinse the rest of the pods off the roots before going in a hydro system. This did cause some shock to the little plants, but they recovered very quickly.
I checked out the rooting plug you use. They claim that they are OK for hydroponics. But it seems that I often run into ph issues with stuff made from peat moss. Again I never have ph issues with the Root Riot brand plugs.
I think all starter blocks have some kind of issues with them. It’s been my experience to get the roots to grow out of whatever starter block is used as fast as possible, and get them pushed out into the water. The aeriated water table is only a couple inches below the bottom of this mini cube, but I’ll start lowering it as soon as I see roots poking out of the 6" netpot it’s in. I keep the moisture up with plastic over the hydroton that I’ll remove once the system and plant have stabilized. It’s just this putting-down-roots phase that’s tricky to get through.
Oh, and I just upped the EC today, from 1.0 to 1.6, as it was looking a little light. Just thinking you might be a little low yet. Hopefully mine didn’t go too strong… I guess we’ll both see 
