rocks overflowing the cups
 

Hi Ron,

I have a dumb question: the "gro-rocks" I have tried (both the expanded clay and pumice ones) float on top of the nutrient solution making it difficult to keep them from overflowing the cups. Is that normal, or are the "gro-rocks" in Arizona full of helium?
gary

You are letting the water rise to high. About half way up the grow rocks is high enough as long as the plant roots get soaked. Actually the rocks that float are the good ones because they hold more oxygen.