Hiyas Folks.
For some reason I am having trouble transplanting new seedlings to a DWC bucket. The keep croaking on me. I had the first few work just great and grew huge. Cleaned the buckets and clay pebbles. Ph is right and added the same nutrients. But they either seem to burn or just fall over. Only thing different since it seemed like in one tent they burn I cut back on the hours of light but leave the air and pumps on. Lost about the last 8 tries and don’t get it.
Thanks for any ideas. I would pay you back with some of the crop. But know that won’t happen mailing from this state.
How are you watering?
Pictures would help also.
Are you top watering until plants can grow roots down into solution?
Just as it shows there. Get a nice root ball in the Rock Wool and put it just above the water line. It worked just fine the first few times. I cut the plastic wrap off the sides of the rock wool to let them go. When I pulled a couple plants out the roots were about the size of a basketball. And they were real nice plants. The roots were in the water from the start but just barely. It’s just strange how one tent burns them and the other they just fall over and that’s it.
Burning and falling over to die sounds like they’re not getting into solution is all.
Me personally i would let the seedlings get a good root system before moving them into the dwc you want the roots to already be hanging out of the rockwool thats just my opinion on how i would do it
I meant roots long enough to reach though into the medium but that comes with time same growth 
I let mine get a bit bigger before they get the big bucket. Takes about 4 weeks from seed to the big tent.
Roots should be long enough to reach the bottom of the basket. Water level should be touching the basket that first week. Keep an eye on your roots extending into the solution of your bucket before reducing water level.
So basically they stay submerged.
Also I use a bit more light in the blue spectrum to try and keep them from stretching during the seedling stage.
Day 1 in tent.
Day 25
I keep the top of the rock wool above my pebbles so that they don’t dampened off and use a beneficial bacterial agent like HYDROGUARD to colonize the root zone with bacteria that prevents the bad bacteria from cause root rot and other bad things.
I always start my seedlings/clones in my rooting box with RapidRoot and TakeRoot powder.
General Hydroponics RapidStart Rooting Enhancer Promotes Root Growth For Seedlings, Starts & Transplanting, 275 ml https://www.amazon.com/dp/B004JWASTS/ref=cm_sw_r_cp_api_glt_fabc_11NB4JAXV97JVWTX2RP6?_encoding=UTF8&psc=1
Garden Safe Brand TakeRoot Rooting Hormone 2 Ounces, Helps Grow New Plants From Cuttings Amazon.com
The first 4 weeks are always the toughest for me.
Good luck in the future.
Stretching indicates insufficient light. So that needs to be addressed. RR should be flush with top of hydroton or below and top-watering done until roots reach into solution. Distance from bottom of net pot to solution should be between 1 1/2 and 2" below and enough air to air stone to splash onto bottom of net pot. 24/0 lighting until established.