Specially formulated to counteract the alkaline nature of rockwool, this Rockwool Formula One improved nutrient is naturally pH buffered and more stable for the entire life of the nutrient solution. Rockwool Formula One is intended to be used as a two-part nutrient mix. The nutrient ratios for parts A and B have changed. Part A is now (5-0-4) and part B is now (1-5-5). Comes with updated mixing instructions. Rockwool Formula One is well-suited to both vegetative and flowering stages.