Whether you’re growing hydroponically, with aquaponics or in soil or soilless media, your pH will always have importance. But what exactly is pH? It is a measurement of how acidic or alkaline a substance is when measured on a scale from 1 to 14 (1 being the most acidic and 14 being the most alkaline). The measurement is depending on the amount of hydrogen ions are in the solution, which is why pH stands for probable hydrogen.
The next question that most growers ask about pH is the ideal level to the decimal for your plants. If you ask five growers this question, you will most likely receive five different answers. Normally, when growers asked me this question, I rephrase it from what is the exact pH to what is the most productive pH range for my plants.
The most productive range is between 5.8 and 6.8, but my recommendation is to not get caught up on being so precise. As long as you are within that range, the majority of all macro- and micronutrients will be readily available for the plant to take up.
Still, many times I have worked with growers that had the perfect growing environment, great cash flow and more than enough light, but still had a low yield because of pH imbalance in the growing media. So, be sure to keep on top of your levels.
Many growers are also looking for an organic method to raise and lower their pH. You can indeed control your pH without ever messing with any chemicals by using basic products. If a grower used beneficial fungus, nitrogen-fixing bacteria and highly chelated mineral deposits (such as rock dust) before planting in any growing medium and working keeping the ppm under 800, that grower would rarely run into a nutrient-lockout issue.
The reason why is because when you grow organic, your entire ecosystem is working in harmony and with the same goal in mind: the plants survival. When your crop is not utilizing microbiology, the plant is completely reliant upon this grower. This is like it skydiver jumping out of the plane without a backup parachute.
Oh, speaking of ppm, remember that ppm, TDS and EC are all the same thing. EC measures the electrical conductivity of your water (remember, everything in this world—even down to the molecular level—has an electrical charge). In other words, EC measures the amount of salts in your hydroponic system.
When you have less salts in a system, you have a lower EC; if you have more salts in a system, you will have a higher EC. Then, while TDS stands for total dissolved solids and ppm stands for parts per million, these readings provide you with the same information as EC. When someone asks if you know your TDS/ppm, all he or she is asking for is a reading of how many salts are in your hydroponic system.
In a regular hydroponic system, the most experience growers will recommend that you have at least an EC reading of 1 to grow anything in hydroponics. If you are growing in an aquaponics system, you could grow full tomatoes with an EC reading of 0.2.
I personally have seen great produce produced using an EC range of 0.2 to 3.6, the levels depending on the growing method and the crops being grown. There are charts available detailing ideal levels, but many like to experiment and figure out what works for them. Just remember that when your EC is too high, you will normally see all your worms leave the environment. All of your beneficial fungi and bacteria go dormant after about 1.6 EC or 800 ppm/TDS.
Then, when you know the EC, ppm or TDS of your system, you can then decide if you need to add something to your solution, leave it alone or dilute it. One of the best ways to control your EC, TDS and ppm organically is to use reverse osmosis (RO) water. By doing this, you have the ability to use a fifth or less fertilizer than conventional farming.
You can get an RO system for less than a couple hundred bucks, but it’s better to not be cheap on this. Clean water is our friend! Keep in mind that, ideally, you want to start with a lower ppm or EC (as when you start with a higher ppm/EC, you cannot take it away).
Also, remember that less is more—water will always be taken up and evaporate faster than your salts are taking up by your plants. As such, always monitor the water levels. If you are noticing your plants taking up a certain amount of water, then I would recommend adding at least that much water every day. If you are growing in soil, I would recommend feeding once and using only water one or two times before the next feed. This will allow your plants time to process the nutrients.
So, if you’re going to take the time and resources to grow, be sure to take the time to also check your pH, EC and ppm. You can measure pH, EC and ppm with inexpensive tools that are sold at your local hydroponic store. Sure, they’re small things, but remember that success is normally a collaboration of small decisions that went in your favor over a long period of time.