Water crystals are perfect for giving to your crickets. Crickets tend to drown, even in shallow water. Water crystals mitigate that risk by absorbing the water into a jelly like substance. This way they can walk on the crystals, and hence don't drown.
Simply get a washed bottle cap or jar lid. Add between 1/3 to 1/2 a teaspoon of water crystals to your dish then fill it with water. After a minute or so, the crystals will turn to a jelly like substance. Put your dish in with your crickets and watch them enjoy!
Each jar contains approximately 15 teaspoons of water crystals.
