Are you talking about something like perlite or vermeculite? Those both are accepted mediums in hydroponics....although I don't think they are used too commonly because they seem to be "messy" to work with....that's only what I've heard....never tried it. :stoned:
Weedhound Reviewed by Weedhound on . Growing in only absorbent polymer crystals? I was wondering if it would be possible or if any one has tried to grow in absorbent polymer crystals only or with a perlite mix in it for aeration? I am sure this can be done and might work well just want to know if anyone has done it with success. Our am I just wasting my time looking at this option. Rating: 5