chattiesmom
I would certainly give them a try. They say they are potassium-based rather than sodium-based, and were specific for agriculture. So I don't think there is anything in them that's harmful to plants. Although without having some in my hands to see how solid they are when saturated with water, it's hard to say that small pieces wont eventually break off and clog a
pump or filter. But I'm sure you could design the system to take that into account. Like creating a catch screen using furnaces filter screening/swamp cooler screening etc., in the overflow/return back to the reservoir, making it easy to clean out regularly. Or even just using a water culture type system, or even a wick system rather than a system that needs a water pump. You may also want to use a light strength
nutrient solution (something in the range of 50%-80% strength) at least at first, until you can judge how the plants are doing.
If I'm not mistaken they may even be reusable, I think they are supposed to shrink back up to their original hard form when dried out. If so, that may make it fairly easy to separate the roots from the crystals after the plants are harvested. However, sanitizing them for reuse may be a problem because they absorb any liquid they come in contact with. I would probably try using H2O2 (hydrogen peroxide) for that, but because they absorb so much liquid that may take a lot of H2O2 even diluted with water. Boiling water would do the trick, but may damage or disintegrate the crystals, same with bleach water. But considering the price, they sound economical even if you don't reuse them. They seem about the same price as coco coir.
P.S.
I would make sure they were not exposed to light, because I'm sure they would grow algae fairly quickly. Mainly because they are clear, making it easy for light to pass right through them. The
nutrients are the food source, and food+water+light= algae.