In hydroponics, sodium hypochlorite solutions are commonly used to sterilize a hydroponic system prior to use or in between different crops. However, this does not achieve the purpose of maintaining the nutrient solution sterile throughout the whole gardening cycle.
In order to achieve this in a very simple way (for the home hyroponic and commercial gardeners) several peer reviewed papers have studied the effect of hypochlorite ions on different plants and at different levels of concentration. In general, it has been found that concentrations of hypochlorite of 5.5 ppm offer good protection agains microorganisms without affecting the crop qualities.
If you do not have any industrial grade hypochlorite you can still achieve this concentration by applying 0.1mL of Clorox (check that it is less than 6% hypochlorite, usually 5.25%) per liter of nutrient solution. This can be easily measured and applied for small systems with the aid of a 1mL syringe as the ones diabetes patiens use for insulin (these syringes can be easily purchased at any pharmacy). Remember to try this with a small batch of plants before applying it over your whole garden to ensure compatibility with your particular nutrient solution.