NFT Gro Tanks Unrestricted access to oxygen - without the need for a timer! Gro-Tanks give roots virtually unrestricted access to oxygen. Yields are typically 3x bigger than if growing in pots. Plants are placed in rockwool blocks and the roots grow along the planting channel benefiting from superb access to oxygen. Nutrient solution is constantly pumped to the roots, there's no timer to programme. Because virtually no growing medium is used there's nothing to transport or throw away at the end of the season.