Any grower, despite the best of preparations, will undoubtedly encounter nutrient imbalances during their crop cycles. Nature is unpredictable and there are a myriad of factors that can influence how your crops will perform throughout a growing season. This is not exclusive to soil or outdoor growing; Hydroponic growing is not exactly more reliable, rather having its own set of risk factors. When you take control of the environmental factors - light, humidity, nutrients - you had better be sure to have a contingency plan in place for when things go off the rails.
Hydroponic gardening is environmentally friendly as it is a closed system and requires less water than traditional soil-based grows. Hydroponic growing also has the benefit of reducing waste and pollution from soil run-off.