What is ORP Meter?
Hydroponic breeders are accustomed to using pH and EC meters to monitor their growth conditions, but very few use ORP meters to learn more about their nutrient solution. An ORP meter can provide you with very useful information, and you can usually buy a cheap ORP meter on ebay or amazon for less than $ 20. Today we will talk about ORP meters, what they are, what they do and how you can use them in your hydroponic product.
One meter of ORP or “redox potential” determines the electrochemical environment in a solution. An ORP meter has two electrodes, a traditional reference electrode with known potential and a platinum electrode whose potential varies depending on the intensity of the solution pressure to take an electron from a platinum electron or give it an electron. A solution that has a lot of material that tends to give electrons has a more negative reading, and a solution that has more material that takes electrons tends to have a more positive reading. ORP readings are given in mV.
So how is this useful in hydroponics? It is useful in this regard that we can know exactly how the chemical environment behaves. The ORP of drinking water is generally around 600-700 mV because oxidants – substances that tend to capture electrons – are added to solutions to kill pathogens. The chemical medium must have an ORP above 600 mV to kill harmful fungal spores and bacteria. Of course, this means that if you want to run a sterile hydroponic environment, you should probably keep your ORP solution in the range of 300-500 mV, large enough to stop the growth of microorganisms, but small enough to prevent From any damage. From happening to your roots
This way you can use things like hypochlorous acid and hydrogen peroxide to increase the “lethal power” of your solution, while also knowing how hard the chemical environment is. ORP also gives you clues about water oxygenation and biological activity in the water. A reducing medium – ORP below 100 mV – means that there are a significant number of substances in solution that want to give electrons, and these substances are generally organic acids, bacteria, viruses or other organic molecules such as reducing sugars. Are. If so, it means that the oxygen in the solution is short-lived, so you want to increase your oxygen significantly or your roots may be deprived of this essential nutrient.
The chemical environment is determined by the types of semi-reactions that can occur in the solution, and this is also determined by the pH of your solution. The table above shows some of the most common electrochemical half-reactions that can occur in solution. For example, to reduce molecular oxygen and obtain 4 electrons, we need to produce hydroxide ions. This means that oxidation reactions tend to increase the pH and are therefore expected to harden with increasing pH. We also have the opposite case for hydrogen peroxide, in which a more acidic solution is restricted to molecular oxygen to prevent oxidation of the peroxide. It is worth noting that these are half of the reactions, so in reality what always happens is that the two halves of the reaction – for example, oxygen depletion and iron oxidation – come together to create a chemical change in the environment.
Finally, ORP measurements give you what pH and EC measurements do not tell you, which is what the chemical environment looks like from an oxidation reduction perspective. With this information, it becomes easier to diagnose things like insufficient oxygen, whether you are adding too much hypochlorite or peroxide, and whether or not you should add more or less germs to your environment.