Increasing Automation with Autodosers

An indoor horticulturist may use many different automation devices to increase the efficiency of his or her garden. Light timers, thermostats, humidistats, and CO2 controllers are all automation devices commonly found in an indoor garden. Another automation device that has become more popular among indoor gardeners is an autodoser. Autodosers, also known as nutrient dosers, are devices revolutionizing the way horticulturists monitor and maintain the nutrient concentration within a hydroponic nutrient solution or automated irrigation system. Like other automation devices, autodosers are designed to increase overall efficiency and reduce labor.

What is an Autodoser?

An autodoser system is a network of equipment that helps maintain nutrient and pH levels in a hydroponic system or automated irrigation system. Autodosers measure the pH and/or the concentration of nutrients within the reservoir and automatically make adjustments to bring these concentrations to preset levels. An autodosing system ensures stable chemical levels, prevents overcorrecting and underfeeding, saves on labor, and avoids sudden changes in the nutrient solution parameters. Autodosers inject nutrients into the hydroponic system’s water reservoir or water feed lines, and they are designed to maintain precise parts per million (ppm) levels within the nutrient solution. Most autodosers include a controller or work in conjunction with a controller that monitors the concentration of chemicals in the solution and triggers the system to make adjustments when needed. There are many different autodosers on the market, but all serve the same basic purpose: to monitor and control the nutrient concentration and pH levels of the nutrient solution. Most autodosing systems can be broken down into three main parts: the monitor/controller, the pump/injector, and the sample reservoir.

Monitor/Controller

The monitor/controller is arguably the most important component of an autodosing system. It is a computer that, with the use of a probe, takes readings of the nutrient solution from within the sample reservoir. From these readings, the controller can determine if the solution is within the desired ppm and pH range. If a reading is out of the desired range, the controller triggers the pump/injectors to add nutrients or pH buffers to the solution. The system takes another reading and continues this cycle until the desired concentration is achieved. Some controllers take readings at predetermined intervals (say every five or 10 minutes), while others allow the horticulturist to set the duration of the intervals.

Each autodosing system is a little different, but the most common set-up is a system that can handle four different solutions for injection. This is likely because the most common hydroponic nutrients are still three-part (micro, grow, bloom) solutions. An autodoser that can handle four different chemicals is able to administer a three-part fertilizer, plus one pH buffer solution. Typically, a hydroponic gardener will use only one pH buffer solution because the pH of a hydroponic nutrient solution tends to drift in only one direction. Although systems set up to handle four chemicals are the most common, there are autodosing systems that can administer up to eight different chemicals.

Pumps/Injectors

The pump or injector is the component of an autodosing system that pumps or injects the nutrients or pH buffer into the hydroponic system’s nutrient solution. The injectors/pumps are controlled by the monitor/controller and are triggered by electricity or by water flow. There are three types of injectors/pumps commonly used in autodosing systems: gravity-fed solenoid valves, water-powered injectors, and peristaltic pumps.

Gravity-fed Solenoid Valves

Gravity-fed solenoid valves are injectors that require the concentrated nutrient to be stored above the valve and rely on gravity to create the flow of solution once the solenoid is triggered. The monitor/controller electrically triggers the solenoid to open, which, with the help of gravity, allows the concentrated nutrients to flow into the solution.

Water-powered Injectors

Water-powered injectors are triggered by the flow of water going through the injector. These types of injectors also have a solenoid or pump connected to the water line. When the controller triggers that solenoid or pump, it forces water through the injector, activating the water-powered pump within the injector and injects concentrated nutrients into the solution.

Peristaltic Pumps

Peristaltic pumps are electric pumps that are triggered via electricity to the pump. The biggest advantage of peristaltic pumps in an autodosing system is the nutrients can be placed below the injection point. This reduces the chance of a spill or an over-concentrated solution in the rare case of an electrical failure or injector failure. This also allows for much larger volumes of the concentrated fertilizers to be used, which reduces labor in the long run. A peristaltic pump is typically a more expensive option but is usually a better long-term investment.

The Sample Reservoir

The sample reservoir is a small reservoir that holds some of the nutrient solution for monitoring. The probes from the controller/monitor take the readings from the sample reservoir. As adjustments are made, fresh solution is circulated into the sample reservoir and monitored again. Some autodosing systems do not have a dedicated sample reservoir, but instead take samples from the main nutrient solution reservoir.

Autodoser Advantages

There are two main advantages of using an autodosing system in an indoor garden: saving on labor and heightened consistency. A horticulturist may spend an average of 20-30 minutes per day monitoring and adjusting the hydroponic nutrient solution. Over the course of a grow cycle, an autodoser can free up many hours of the grower’s time and the gardener may choose to spend that extra time increasing the efficiency of other areas in his or her garden.

Heightened Consistency

The biggest advantage of using an autodosing system is not the labor savings, but the heightened consistency. Plants respond best to consistent conditions. Problems in an indoor garden usually occur when atmospheric conditions or the parameters of the nutrient solution change suddenly or fall outside of the desired range for an extended period. Experienced growers understand that consistency is the key to unlocking an indoor garden’s full potential. Autodosers offer the best available solution for maintaining consistent nutrient solution parameters.

Hydroponic growers typically measure nutrition concentration by using ppm, total dissolved solids (TDS), or electrical conductivity (EC) monitors. A gardener normally has a desired range in which he or she wishes to keep the nutrient concentration. Daily monitoring with ppm, TDS, or EC monitors allows a grower to adjust the nutrient solution’s concentration when needed to maintain levels within the desired range. Unfortunately, the concentration of nutrients and the pH of a nutrient solution can fluctuate out of the desired range in a relatively short period of time. Sometimes, this occurs quickly enough that even daily monitoring and adjustments will not correct the inconsistent nutrient and pH values. In extreme situations, a sudden change in the pH or nutrient concentration can cause stunted growth or even nutrient lockout.

Many autodoser controllers can be set to monitor and make adjustments as often as every five minutes. This ensures the nutrient solution’s parameters are kept as consistent as possible at all times. With a consistent nutrient concentration, the plants will always have what they need when they need it. Also, by maintaining a consistent pH value, the plant’s ability to uptake those nutrients will not be compromised.

Avoid Human Error

Another factor to consider is human error. It is not uncommon for a grower to make a mistake or to overcompensate when adding nutrients or pH buffers. Implementing an autodosing system reduces the likelihood of human error and leads to more consistent nutrient levels and a balanced pH for the duration of the plant’s life.

Autodoser Limitations

Autodosers are incredible automation tools, but they do have their limitations. For example, autodosers measure TDS and do not adjust for individual essential elements. In other words, an autodoser cannot tell when nitrogen or another individual element is being used by plants at a faster rate than the other nutrients present. An autodoser only senses when the total concentration of nutrients has diverged from the desired range. What this means is that growers using autodosing systems should still do a complete reservoir change on occasion. Otherwise, the nutrient solution could become unbalanced and the plants will not be receiving what they need. Growers with autodosing systems can generally wait longer between reservoir changes but should still perform a complete reservoir change periodically.

Automation devices for indoor growers are valuable tools. They allow a horticulturist to not only save time and labor, but also create more consistent conditions conducive to accelerated plant growth. An autodoser is a vital tool for hydroponic growers who wish to provide their plants with the most consistent nutrient and pH levels. Both hobbyists and commercial growers are reaping the benefits provided by implementing an autodosing system. Although autodosing systems can vary from manufacturer to manufacturer, they are all designed to provide the same basic function: to automate the delivery of nutrients to create the most consistent nutrient and pH levels possible.