A healthy root zone is the ideal situation in all hydroponic systems
Nutrient solution disinfection can be used in both solution culture and substrate based hydroponic systems .
Disinfection can assist with preventing the spread of root rot pathogens such as Pythium .
Crops such as spinach which are prone to Pythium in recirculating systems often make use of disinfection methods .
During treatment , the UV equipment passes light from the UV lamp through a thin film of nutrient solution . For the process to work effectively the solution must be clear and often pre filtration is used to remove any organic matter or other material first . The recommended UV dose rates for disinfection of recirculating systems is 100mJ . cm-2 for control of pathogenic fungi and 250mJ . cm-2 for control of all pathogens including viruses . When using smaller UV units it is important to obtain the correctly sized unit for the volume of solution to be disinfected and to replace the UV bulbs once the usable life of these has passed ( UV bulbs will only be effective for a certain number of hours before they need replacement ). The downsides of UV treatment are that these systems do not discriminate between pathogens and non-target or beneficial microorganisms , and UV can effect iron chelates in solution , requiring higher rates of iron application and use of the most stable chelate forms such as Fe-EDDHA .
Ozone
Ozone treatment of nutrient solutions requires an ozone generator onsite that discharges ozone enriched air as small bubbles into the solution flowing through a venturi . Ozone dissolves from these bubbles into the solution over a certain contact time and reacts with organic matter including pathogens . One of the major benefits of ozone treatment for water or nutrient disinfection is that any ozone which has not reacted reverts to oxygen , which in turn increases the dissolved oxygen content of the solution . This has the potential to improve crop growth . Ozone generation systems must be installed correctly as off-gassing into the air surrounding the crop can cause crop damage . Ozone destroys pathogenic microorganisms and leaves no residue in the nutrient solution that might be toxic to plants , however , ozone treatment can break down iron chelates and may cause precipitation of manganese , so these trace elements need regular monitoring .
Filtration
Membrane filtration can be used to remove pathogens once coursergrade filters have first cleared the solution of larger organic particles . Hydroponic water and solution filtration methods include micro filtration ( pore size 100-1000nm ), ultra filtration ( 10-100nm ), nanofiltration ( 1-10nm ), and reverse osmosis (< 1nm ). The most efficient membrane filtration systems use combinations of different filters to progressively remove smaller and smaller particles as the solution flows past . Membrane filtration has been shown to be effective for several different pathogens , however , such systems require regular maintenance to keep the system working effectively .
42 Maximum Yield