I started using cotton flannel in 1020 trays last year and doing some bottom watering. That helped, and itg especially helped that the flannel wicked away what would otherwise have been excess perched water in the bottom half of the cell.
But it was mixing in bark a year or so before that, that stopped my seeds from rotting and stems from damping off. That in initial delightful success made it "my way" and I'm slow to set aside an innovation that made a night-and-day difference for me. I'm still too proud of it!
I think it also helped that I stopped using a bag of Miracle-Gro seedling mix that, I swear, was like finely powdered peat. Recently I bought a local mix form Steubers that looked about 20 times better than that peat powder.
So maybe the better mix and cotton capillary mat would work by themselves if I never watered the cells until water came out the bottom. After all, a seed-starting cell can't accumulate toxic levels of salt the way a permanent container can. But I think it may take a few thousand seedlings for me to actually break the over-watering habit.
I know the bigger chunks are "wasted space" as far as root hairs are concerned.
I only add a little, finer, bark to Petunia and Alyssum cells.
As far as I know, I'm the only person who thinks bark is better than sliced bread for seedlings. Containers and heavy clay in raised beds, sure, I'm not crazy to use it there.
If I start weaning myself away from it now, I might eliminate the bark-and-overwater habits by the time I retire. But then finances will drive me to start using bark again.
