Measuring and Adjusting pH
As discussed in our article titled “Cannabis Fertilizers, Supplements, and pH” measuring and adjusting pH level of the nutrient solution has a significant impact on the solubility of nutrients within the solution. When the pH of the added solution falls outside the acceptable range, some nutrients become unavailable to the plant.
Acceptable pH Range for Coco: 5.5-6.5
Coco doesn’t buffer the pH of the nutrient solution as effectively as soil does. Therefore, it’s crucial to ensure that the pH of the incoming nutrient solution falls within the range of 5.5 to 6.5. Since different nutrients have varying solubilities at different pH levels, it’s advisable to allow the pH to naturally fluctuate within this range during successive feedings. For most of the growth cycle, aim for an average inflow pH of around 5.9. However, during the seedling and ripening phases, it’s best to target a somewhat higher pH within the range (around 6.1-6.3).
Measuring pH:
There are two primary methods for measuring pH: using a color indicator test with liquid drops or employing a pH meter.
pH Meters:
pH meters come in a range of prices, from around $15 for basic models to over $100 for advanced ones. It’s worth avoiding the cheapest meters as they tend to be unreliable and have shorter lifespans. However, you don’t necessarily need the most expensive meters either. A recommended option is the Apera Instruments pH meter, which comes with calibration fluid for ease of use.
All pH meters require regular maintenance and calibration. While many meters come with calibration powder, it’s better to invest in pre-mixed calibration fluid for accuracy. Between uses, store the meter in either storage solution or calibration fluid, ensuring it is immersed up to the “immersion line.”
Bluelab PENPH pH Pen
Adjust Inflow pH:
Most nutrients and supplements added to the nutrient solution have an impact on pH. Base nutrients typically lower the pH, while certain supplements like silicon and SM-90 raise it. The degree to which you need to adjust the pH of your nutrient solution depends on your starting water’s pH and your specific recipe for each growth stage.
Allow nutrient solutions a few minutes to stabilize before measuring pH. To adjust pH, it’s advisable to use products designed for horticultural nutrient solution pH adjustment, such as General Hydroponics “pH up” and “pH down” products. These allow significant pH adjustment with minimal doses and minimal impact on the EC of the nutrient solution. Generally, less than half a milliliter of either product per gallon should suffice for pH adjustment. After making adjustments, always re-measure to verify. Recording inflow pH values in your grow journal is recommended.
pH Control Kit
You need to have a way to adjust the pH of your water and your nutrient solution. We recommend that you use products engineered for this task because they allow significant pH adjustment with very low doses and have minor impact on the EC of the nutrient solution.
General Hydroponics pH Control Kit
For the US and Canada, we have linked the General Hydroponics pH Control Kit. It comes with both pH up and down. It also includes a color test kit for measuring pH. This is all you need to start managing the pH of your nutrient solution. We recommend using a pH meter (see above) instead of the color test, but having the color test is great for periodic verification. The kit is not currently available in the UK.
Ignore Run-Off pH:
While adjusting the pH of the inflow is crucial, there’s no need to be concerned about the pH of the run-off water. Your primary focus should always be providing nutrient solution (inflow) within the appropriate pH range. Some growers mistakenly attempt to correct run-off pH values by providing nutrient solutions outside the acceptable range. This can disrupt the pH of the nutrient solution in the root zone and render nutrients unavailable. To avoid this common mistake, simply disregard the pH of the run-off.
For a complete guide on nutrient mixing for cannabis, please refer to our tutorial titled “How To Mix Nutrients Solution for Cannabis.”
Related Articles
- Nutrient Supplements That We Recommend
- Cannabis Fertilizers, Supplements, and pH
- The Importance of using CalMag in Coco
- How to Mix Nutrient Solutions
Set-up Your Grow
Growing Cannabis
- Cannabis Seeds
- Fertilizers & Supplements
- Propagation Supplies
- Plant Training & Care
- Harvest & Processing
Want to Receive our weekly Newsletter full of Grow Tips, News and Exclusive Content? Subscribe Below!
About Our Product Recommendations
Here at 420 Grow Help, our primary goal is to assist growers in achieving the utmost success with their cannabis crops by providing accurate scientific information and sharing proven cultivation techniques. The products we recommend are the very ones we have personally chosen to purchase and use ourselves. We maintain a strict policy of not accepting sponsorships or advertising, and we only endorse products that meet our own high standards. For detailed product recommendations, please refer to our Product and Equipment Guide.
Please note that when you make a purchase through the links we provide, we may receive a referral fee. This is the primary source of revenue that supports and sustains 420 Grow Help. By clicking through our links and making purchases, you are directly contributing to our ongoing work. As an Amazon Associate, we earn from qualifying purchases.
Disclaimer:
The information presented on 420GrowHelp.com should not be regarded as financial, legal, or medical advice. It is your responsibility to familiarize yourself with and abide by the local laws and regulations pertaining to the cultivation, possession, and use of cannabis. Decisions regarding cannabis cultivation should be made in consultation with a lawyer or qualified legal advisor, while decisions regarding cannabis use should be made in consultation with a doctor or medical professional.
