Sampling, Adjusting, and Rinsing
Of course, it takes more than an understanding of what pH, EC, and TDS signify to put these concepts to use with hydroponics. Following the directions provided with a hydroponics-specific nutrient mix should be enough to get off to a reasonable start but testing and adjustment will be needed thereafter.
Most hydroponic growers set up a regular testing schedule, typically after deciding how to obtain samples. The simplest option is to take a number of nutrient solution samples from evenly spaced parts of a system, and then measure and record the pH and EC or TDS of each.
Once those measurements have been analyzed, the samples can be combined to enable an aggregate reading. That should give an idea as to the overall health of the system, just as individual samples provide windows on particular parts of it. When issues arise with either pH, on the one hand, or EC or TDS, on the other, the following responses will normally be in order:
- If the pH of the system has dropped below 5, adding small amounts of a base like potassium hydroxide can help raise it. Should the pH rise above 6.5 or so before plants have started flowering, diluted nitric acid can be added to push it back down. Later on, diluted phosphoric acid is more often used, with products containing each often being labeled with the developmental stages they are intended for. Always make modest adjustments to pH, wait for the system to stabilize, and then sample and measure again. Otherwise, dangerously large swings can result.
- EC or TDS. EC should normally be maintained between 0.8 and 1.8 mS/cm throughout the growth phase and then dropped to 0.4 and 0.8 mS/cm while plants are flowering. An overly low EC reading is a sign that nutrient levels need to be increased. If EC levels rise too high, adding more water to the system will lower them. Because evaporation removes water from a system but leaves salts behind, EC and TDS readings will tend to climb on their own over time, even when everything is in order. The hardness of the water used in a system, as expressed by its TDS, will also impact the effectiveness of nutrients used to adjust EC. Harder water will take a smaller proportion of the nutrients into solution, requiring larger additions to achieve the same boost to EC.
Regular measurements and indicated adjustments should be used to keep pH, EC, and TDS levels as stable as possible. Flushing or rinsing the growing medium as needed is the other key to keeping conditions within a hydroponic system favorable to growing our regular and feminized marijuana seeds.
Rinsing the medium removes built-up salts and any debris that has accumulated within it, allowing for an essentially fresh start. The system can also be flushed before harvesting to encourage plants to use up nutrients they have stored. While this might reduce yields somewhat, it can improve quality while also setting a hydroponic system up for the next crop. When it comes time to re-order your hydroponic marijuana seeds, we hope that you can take advantage of the great deals on American seeds available at weed-seeds.com