Maximum Yield USA 2015 April | Page 114

the power of orp “Keeping the killing power constant, at a reading determined to be fit for your application, is critical to keeping pathogens and diseases non-existent in a hydroponic system.” So, let’s say you decide to use ORP as a means of maintaining a sterile and disease-free environment and you have access to an ORP meter. How do you use the readings to make decisions about your system? If you are facing a potential plant disease, research suggests water with an ORP of 680 mV or higher can kill pathogens such as pythium and root rot in less than three seconds. Water with an ORP this high can kill the E. coli bacteria in under three seconds as well. Under normal conditions, and when a pathogen is not suspected to be present, maintaining an ORP reading of approximately 420 mV is considered safe and effective. Keeping the killing power constant, at a reading determined to be fit for your application, is critical to keeping pathogens and diseases non-existent in a hydroponic system. Although the study of ORP contains a lot of twists and terms that seem to be misleading, it is a relatively straightforward factor to control. Whether you are growing organically or otherwise, keeping an eye on ORP has its benefits. If you implement reducers, such as beneficial micro-organisms, as a part of your organic system, eliminating oxidizers will keep the ORP and killing power low, making sure you aren’t canceling out the benefits of one resou