Nutrient lockout happens when your plant can not access specific, or all nutrients in the growing medium, this is due to a chemical reaction within the medium/solution which prevents nutrients from being absorbed by the roots. Aged nutrients can precipitate in the bottle, causing some of the ingredients to become solids or even evaporate, the same problem may also occur in the growing medium. Lockout will display the same symptoms as nutrient deficiency; to help control this problem dispose of old liquid feed containers as you would old medicine and use fresh nutrients from a bottle that has been recently opened. The following points can also be responsible for nutrient lockout. PH is incorrect or fluctuates. Single pack hydroponic solutions. Salt build up. A chemical reaction between 2 or more nutrient solutions that are mixed together. For acute deficiency symptoms caused by toxicity and nutrient lockout a first Aid program should be immediately administered. Step 1) Leach the plants roots and growing medium using a professional leaching agent to thoroughly leach away metals, calcium, sodium, chlorides, sulphates and many other compounds, which can build up in the growing media. Step 2) Feed with 1/4 strength high quality complete plant food mix along with a high quality vitamin B-1 product such as Superthrive (1 drop per gallon). Step 3) Spray a professional stay green formula on the leaves. After 24hrs, spray the leaves with a quality vitamin B-1 product. Feed at 25% of recommended fertilizer dosage until first signs of growth.