Sure to grow™ is a “revolutionary new plant growth medium” 

A 21st century alternative to Rockwool, perlite, and coco coir for hydroponic growers. It’s made from recycled plastic bottles – but feels and looks more like cotton wool! Sure To Grow (STG) is super lightweight, easy-to-handle stuff that boasts all the qualities you would expect from a modern growth media. It’s easily wettable and highly aerated. It’s also pH neutral so no pre-soaking is required. You can store it indefinitely and it’s not irritating to skin. STG is a non-wicking growth media. This means that it has no “capillary action”. STG does not “suck up” and absorb nutrient solution into itself in the conventional way like rockwool and coco coir, for instance. Instead it simply holds moisture within itself in a sort of “nutrient suspension”.