dehydration in lava rock and aliflor

[bethmarie]

I've got a lot of plants potted in lava and/or aliflor. I was cautioned when I got them that these mediums hold more water than people think, which may be true under greenhouse growing conditions, but in my conditions they seem to dry very rapidly. I've got a couple in 2 and 3" pots that have been set back significantly due to my under watering.
I grow indoors under lights, running about 50% humidity, with constant air movement.

I'm hoping to hear your experiences with these mediums, and tips from those of you who have plants thriving in one or the other.

Thanks!