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How to Manage Nutrient Supply

“Do you offer a solution for monitoring the nutrient supply including automatic dosing/correction that would eliminate making manual corrections on a daily basis?”

The question is from one of our customers. It is a common question not only for Bifarm Precision Aeroponics system, and also to any indoor farming such as hydroponics. To answer the question, let’s have a look at the nutrient supply in Bifarm’s precision aeroponics setup.

Plumbing lines for growing systems

Two Intakes, one drain; with pH & EC monitoring

As some of you might have known, for commercial setup, the Bifarm Raised Bed comes with one drain and two intakes — one for nutrient and one for water. Water can be used for auto-cleaning purpose among other usages. All intakes are controlled by solenoid valves. The drain is also assisted by a powered pump. And each of our grow system is equipped with pH and EC sensors.

No auto-dosing at unit level, why?

But noticeably it doesn’t come with auto-dosing capability. Why? Is it difficult to build auto-dosers? Considering the system controller provides comprehensive interfaces for thermostats, CO2, grow lights and others, adding auto-dosing capacity shouldn’t be difficult, right?

In terms of engineering, adding several dosing pumps to dispense nutrients is not difficult. However, the answer is more complicated than most of people think.

To do proper auto-dosing, we need to know each ingredient concentration. Solely based on EC reading alone, there is no easy way to adjust for each ingredient. The EC value is used as a proxy to monitor the concentration of the nutrient salt as whole. Since there are many types of ingredients, and each has different impact on EC (Electrical Conductivity), there is no accurate way to rely on EC to do auto-dosing. Universities and research institutes use very expensive equipment to analyze the nutrient content.

In practice, farmers use nutrient company’s feeding table to estimate. Most the dosing-system will use pre-set the formula ratio for dosing, with EC as reference of low / high of the contraction, or dose based on pre-set time schedule, or “topping off”.

Topping-off can lead to burn and deficiency

This type of nutrient dispensing method could cause issues. As plants take in nutrients at different paces over time, the concentration ratio of each ingredient will be hard to predict, if not impossible. “This can lead to burn and deficiency” as one grower puts it.

Dump used nutrient and replenish with new

This is the approach Bifarm is taking. At any time pH and EC sensors detect the nutrient content is out of safe range, the system will dump the nutrient and draw a fresh batch. Also, systems can flush the nutrient periodically, even pH & EC readings are in the safe range. Some of our customers flush weekly. It is configurable at your preference in the GrowOS management suite.

As Bifarm grow systems are using aeroponics method, the amount of nutrient water used is much less than DWC (up to 80% savings in nutrients from our user feedbacks). It is much more practical and cheaper way to ensure nutrients are always balanced.

No recycling = No cross contamination

As illustrated, each grow system draws fresh nutrient and dump it to drain directly. There is no recycling loop among systems. This insulated nutrient supply design reduces the chances of the disease/bacteria/fungus cross-contamination.

Match the plumbing line with grow schedule

In commercial facilities, grow systems are managed by groups, by rooms for example. It would make sense to line together the grow systems running with the same schedule, and supply with one nutrient reservoir. This way, the fresh nutrient in the main reservoir can be adjusted according to the stages of the plants in the schedule. Surely, you can further split the plumbing lines depending on your floor layout. But the idea is the same.

Now to the opening question, in a simplified answer:

  • I recommend individual system should have nutrient quality monitoring capability as much as financially possible.

  • I don’t recommend topping off or continuing dosing to condition the nutrient content. Dump and draw fresh nutrient, instead.

  • Main nutrient reservoir can use dosing system or just manually mix according to nutrient company recommendation. Keep it fresh. Use pH control if needed, when you don’t plan to use up nutrients in short time.

  • Don’t use city water directly. The dissolved solid would negatively impact the nutrient intake. Distilled water or RO water is recommended.

Happy growing.