my thought on the water crystals is, in growing cannabis you need to allow the soil to dry out in between waterings, this product will make this quite difficult and may cause root rot with in-ground plantings, thats my thought on the topic, but given your situation your plants are going to suffer by only being able to haul a small amount of water, come flower time those girls will be drinking like fish, last year ours drank almost 10 gal's a piece towards the end. just giving you some insight, hope this helps
.. should start an adventure 