The nutrient lockout may be caused by the supersaturation of chemical fertilizers with a high salt level. At times, the overabundance of one element can result in the others being locked out. This is a very rampant issue that many growers have come to face. Another quite common issue that can cause nutrient lockout is a false pH value in the medium of growth. A highly acidic or basic medium will lead to nutrient lockout. Ensure your pH level is very close to neutral, within 6.0-6.5.