>> I don't water till the container feels light, and then just by bottom-watering
I only recently made bottom-watering work for me. Moving the trays and immersing them in a bathtub was awful - the bathtub floor sloped, and also the mud clogged the drainpipe.
Now I set a pad of cotton flannel between the water-holding tray and the sheet of inserts or propagation tray. I can water the cotton without submersing any of the cells. The pad also "shares water evenly" among all the cells, so no one gets thirsty until EVERYONE is thirsty.
(Edited to add this link:
http://garden.org/ideas/view/R... )
Now I just have to teach myself that seeds don't need water flowing all the way through the cell every day, the way a potted plant might need to be flushed every few weeks.
(Oh MAN, I'm glad I changed over to FireFox. I'm stuck with IE 7 today and it stinks on ice!)