Yes in nature , the substract is sand and mud... There should be other mineral in the soil. and the good sunlight which make the crypt grow beautifully in nature.I understand that the substrate should be sand with some mud and that the water can be hard (having calcium and magnesium bicarbonate) without being harmful to the plant. Can you tell me more about the water? Do you add fertilizer? If you do, how much and what kind of fertilizer? Do you have fish in the water with the plants? Do you change the water?