What overheats the germination? My mats seem like they have it pretty warm in there.
I had to put a piece of corrugated cardboard on my heat mat
to keep the seed trays from overheating. This year I put the
set-up in my grow shelf and had the T5 lights on and it just
got a bit too warm. Next time I won't turn on the lights until
I see some cotys up.