1 week seedling issues

DWC system - 10 gal tote w/ 2 airstones
600W MH w/ 6" fan 240cfm- started at 3 feet high on 50% power, then moved to 75% power after a few days
PHd to 5.5-6.0
put smallest amount of nutrients (GH trio) in water (1 tsp each for 8 gals)

The 1 seedling (Northern lights #5 X Haze) seemed pretty good at germnation - but since putting in grow tent it hasnt really grown at all. I am supporting the little stem with a piece of paper plate to keep it straight up

The 2nd seed (Jack Herer Auto fem) i think is totally dead. It got its cotyledon leaves and then never decided to completely unfurl. I started germinating 2 more JH seeds today to replace.
steady 73-74 degrees 45% humidity
germinated in Rapid rooter pods - both sprouted in 4 days
Not sure if I should have kept them germinating on their heat mat until I see roots or not? Did I plant in Hydroton too early?
is there something else I should have done?
after 7 days it should be a little bigger I think, not to mention why the other one died.....
Any thoughts are appreciated - 1st ever grow

Maybe you need more air stones. I received an almost dead(frozen) clone in a rapid rooter. I put it in one of my tables. The rapid rooter made a horrible mess in the res and the clone died anyway.

I'm not saying the problem is in the rapid rooters. Maybe these people that recommend rapid rooters don't do hydro.

My guess is your seedling passed away due to a lack of irrigation. Whatever the problem is with your DWC is marginal as the one seedling is hanging in there.

Planted too early or the solution was not high enough or . . .. Keep on the heat mat until you get good roots.