In simple terms, these are the basics of ph and ec in your nutrient solution.
pH of the Nutrient Solution
pH is a measure of how basic or acidic a solution in terms of dissolved Hydrogen ion (H+) concentration. So why do you need to monitor and maintain the pH? The answer is simple – it determines the availability and absorption of nutrients by your plants. The optimal pH range of a hydroponic nutrient solution should be 5.5-6.3 and roots assimilate nutrients best within this range.
Consequences of pH Fluctuation
Problems crop up when the pH deviates from this range. If it drops below 5.5, then the solution becomes vulnerable to micronutrient toxicity. This happens because the acidic salts bind to the core nutrients (especially calcium and magnesium) which then become non-absorbent by roots. When the pH goes beyond 6.5 (too basic), the micronutrients and other nutrients precipitate and accumulate on the walls of the reservoir and the growing medium. If the nutrients precipitate out of the solution, plants cannot absorb them. In short plants are stressed when pH is incorrect. That was the significance of monitoring pH for growing high value crops.
The pH is adjusted with the help of a pH meter. You can buy a kit for this purpose. Read the instructions explained in the manual before using the pH meter. Make sure that you have mixed the nutrients properly with water before checking the pH. Dip the pH meter in the nutrient solution and observe the readings. If the pH is higher than the desired level, then add either phosphoric acid or sulfuric acid to lower it. Similarly, if it’s lower than the desired level, then you need to add potassium hydroxide to raise it. Add the acid or the alkali solution very carefully in order to achieve the accurate range without much effort. It is quite possible to not get the ideal range in the first chance and for this you need to practice the technique of adding the acid or alkali to a spare solution. You need to monitor the pH frequently in a closed system because the same solution is recycled to your plants.
CF/EC/TDS of the Nutrient Solution
- CF: Conductivity Factor
- EC: Electrical Conductivity
- TDS: Total Dissolved Salts
CF is the capacity of the solution to conduct electric current. Simply put, EC measures the level of fertilizer salts present in the nutrient solution. The strength of the nutrient solution is measured either by an EC meter, CF meter or a TDS meter. The units used for measuring these values are PPM (Parts Per Million), µS (MicroSiemens) and mS (MilliSiemens). Your high value crop grows happily within 0.75 to 1.5EC and TDS 500-1000ppm. Growth rate of plants gets affected adversely if the EC fluctuates from this range. Electrical conductivity of a nutrient solution is largely dependent on temperature (68-78 degree F).
Another important aspect that you must check is the calibration of the EC, CF and TDS meter. Read the instructions carefully and then use it. Also ensure that it is water resistant, energy efficient and has good quality of electrodes and batteries.
Fluctuation of EC
If the EC goes beyond the normal range, then the root zone of the plants will be damaged severely. Therefore, it is suggested to begin with a relatively weak solution so that the EC remains within the normal range even if the water evaporates.
EC values in different stages of Growth
- Transplantation of seedlings: 500-600ppm
- Peak vegetative growth: 800-900ppm
- Transition from early to heavy flowering: 1000-1100ppm
- Flushing or Harvesting: 400-500ppm
The bottom line is using an EC meter along with a pH meter helps determine the optimum nutrient dose of plants without over fertilization. And therefore you must maintain the optimum values throughout growing.