Originally Posted by stinkyattic
With a pair of tinsnips, cut the rims of those cups RIGHT down to the soil surface. You should never have more than an inch of rim above the soil at any life stage; air flow is necessary or pythium wilt of the seedlings is a real danger.
And get the cups RIGHT up to the light. The leaves of the plant should be about an inch from the tube.
You need another tube in there pretty soon if you are going to grow under tubes. I consider a pair to be the minimum; the multiple points of light are really beneficial and you'll see how when you add it.
Temp is good. Ventilation is necessary. A small fan circulating air IN the cab, plus an exhaust removing air FROM the cab, are both needed.