Wow, I can't believe how long it's taking for these to saturate. Some of them, like the PVA sponge, are barely wet on the tops. Anyway, i filled the water tanks all the way up to saturate the sponges as much as possible, which should speed things up a bit. I also got some measurements while doing it.
Here's the rough running totals (g H2O):
PVA sponge - 10g
Powdered perlite - 20g
Clay dirt - 13g
Sphagnum moss - 20g
Powdered vermiculite - 23g
so sponge and california clay dirt are not the best.