Clay Pebbles have been a favourite hydroponic substrate for many years. The rough surface holds a lot of water, while the shape allows for completely free drainage and lots of air in the root zone. Clay pebbles for growing have improved a lot over recent years. For example, the Gold Label Hydrocorn has an RHP certification meaning it has been tested to be crop-safe, reliable and consistent!
Grow Stones are a new contender in the market and offer up to 3 times more water retention and 12% more air retention than other hydroponic media. Made from completely recycled material they offer the capacity to hold more of both the nutrient solution and air that your roots need to thrive.