No, he's talking about the crystals used to hold water in miracle grow and other soils. They like to call them moisture crystals. You can use them. IT's been done. IT's just like using perlite or a vermiculite/mix. They are silicone based I believe. I might be wrong about that though. You could use them but you would have easier and a less expensive time by using perlite or the mix. You can look for the HEMPY Buckets to help you...
right here...

Derailed - Hempy bucket stylee - UKCultivator
lmdesade Reviewed by lmdesade 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