An Introduction to Automatic Dosing in Hydroponics

Posted by Jason Arnold on January 27, 2016

So you’re thinking about an automated dosing system, but you’re not sure if you can bite the bullet to pay for it. I can sympathize. When someone suggests you may need an expensive new system to run your business, you might be tempted to quietly tip toe away.

Unfortunately, denial is not a good capitalization strategy. The reality is that you may need an automated dosing system to run a commercial hydroponic system. Even so - you can save money (and frustration) down the road by choosing an automatic dosing system that is right for your facility and your needs.Since we went through the purchase process recently, we want to share some of the things we learned about automatic dosing (auto dosing) with you all.

DISCLAIMER: This article is meant for people who don’t have any knowledge or experience with auto dosing systems, although the more experienced growers might find some usable insights here also.

If you're looking for a more in-depth overview of autodosing, register for our free webinar. 

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Why do I need an auto dosing system?

I asked Mark Germino at Aloha Hydroponics how much time he was saving with his Autogrow system. He said he was able to save quite a bit of time managing his four small production facilities. But that wasn’t the reason he chose a dosing system.

“I work with four different production facilities, and so I can save quite a bit of time. But that is not the reason I went with an IntelliDose system. I went with IntelliDose out of necessity. I want everything to be done right, and to remove the human error from the system.”

These are the two comments I hear regularly. A remote monitoring system not only saves you the time it takes to replenish your nutrients, it can also save you the drive time to get back and forth to your monitoring station. And it can prevent crop loss events due to human error. So let’s take a closer look.

Screen_Shot_2016-01-22_at_1.17.09_PM.pngRead more: How hydroponic nutrients are dosed without auto dosing

What is an automated dosing system?

An automated dosing system really does two things: monitoring and dosing.

Monitoring

Using a probe positioned in your nutrient reservoir, the system measures your pH, EC levels, and water temperature.AutoGrow-full-pH_Probe.jpg

These are the most critical variables for your hydroponic growing system. (If you're a beginner, EC stands for electrical conductivity, which uses conductivity to measure the salts in the system. The level of salts present correlates to the level of dissolved nutrients in the water.)

Read more: How hydroponic nutrients are monitored without auto dosing

Dosing

The dosing system powers several pumps to add nutrients or minerals to your system.

Dosing systems can save significant time and labor, as well as protecting against crop shock events; both goals are appropriate for both large and small systems. In fact, small systems can benefit from automated dosing just as much as large systems, since their nutrient levels usually fluctuate more widely than large systems.

What are the benefits of auto dosing?

The most obvious benefit of automatic dosing is that you won't have to spend time testing and adjusting your pH, temperature and EC levels, but the implications of that benefit reach beyond that.

1) Save on labor

Many growers spend 15- 30 minutes a day testing and correcting their system levels. (2-3 hours per week!) This means testing for pH levels, EC levels, and other nutrients as needed. Beginning growers will often spend more time on this until they get a feel for nutrient levels.

2) Avoid over correcting

Many folks unintentionally over-correct one or two of their variables. This is kind of like adding too much flour to the pancake mix. You have to add more water to balance out the flour, but then if you add too much water you have to add more flour. Auto-dosing systems help keep these levels stable, and provides the optimal environment for your plants. This results in bigger, healthier plants.

3) Avoid shocking your plants

Plant shock events can occur whenever a plant experiences a sudden change in environment or nutrient flow.

One common scenario happens when the water is dumped from the system. Some growers do this weekly to start fresh at the beginning of the week with correct nutrient levels. This can be harmful to your plants (as well as being wasteful).

(Read more: Recirculating vs. flow-to-waste hydroponics)mixing-nutrients-2-1024x867.jpg

The reason for this is that the water in the bottom of the tank is usually highly concentrated, with more nutrients left from evaporation throughout the week. After the tank is emptied, fresh water is added with nutrients at the correct levels. When the fresh water (with correct nutrients) is added back to the system, the plants absorb it.

The difference is that now this is a more diluted solution than before. Since plants take up water primarily through osmosis, which uses a diffusion gradient, a change in concentration changes that gradient. Before adjusting, the plants take in a larger-than-normal amount of the diluted solution. This is called "flooding" your plants. It is usually a minor stress on the plants, although if nutrient levels fluctuate too wildly you can shock your plant and even cause crop loss.

The way an auto dosing system corrects for this is by measuring and adding nutrients in real time. The system can take measurements on a scheduled interval. It will decrease nutrient levels by adding water, or, conversely, increase nutrient levels by adding nutrients to the reservoir.

This level of control over your system means that you will dump your system less frequently, which saves you the cost of lost nutrients and results in less waste. The consistent nutrient supply will result in healthier, more robust plants.

4) Keep your freedom to vacate!

When a farmer has to be present all day, every day, to take care of his (or her) pH and nutrient levels, it tends to be a bit binding. Having an auto dosing system can give farmers the freedom to leave the farm for a day or two. It makes leaving the farm in the care of another person easier in case they want to leave for longer as well.

For aquaponic growers: maintain iron and pH levels

Aquaponic growers don't use nutrient solutions. However, many AP growers will still consider an auto dose system for checking for and correcting pH and iron.

How does it work?

When you set up the automated system, you will calibrate your unit to your desired pH, EC and temperature. You will then connect your inputs to the system. For example, we have a reservoir for each of our supplements; part A (main nutrient mix), part B (calcium nitrate with some magnesium sulfate [Epsom salt]), and pH down.

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These will usually be kept in five-gallon buckets with a small hose to connect to the dosing system.  The automated system will take a test every so often, and then, using one of the small pumps that goes with the system, it pulls the supplement from the bucket into your system.

How much does it cost?

A pH monitoring unit alone can cost $300. When you start to add pumps and If you want to be able to control for temperature, EC levels and pH, and to have remote login capabilities, the price can run as high as $4,000.

Additional features

We have covered automation systems for the 3 major nutrient variables; pH level, nutrients mix, and temperature. More advanced systems can also control for climate variables such as:

  • Lighting intervals
  • Temperature
  • Carbon Dioxide Injection (the system adds CO2 to the indoor air environment with a CO2 injector. This system usually burns natural gas)
  • Humidity

Can you recommend a system?

We can safely recommend systems from Hydrofarm, BlueLab, and Autogrow. We recommend that you begin your exploration with a needs assessment to determine exactly what you need, before you begin shopping.preview-full-IntelliDose_Complete_Kit.jpg

We have chosen to use the IntelliDose System, from Autogrow because it is well-made and comes with great customer support. If you have any questions about our experiences with this system, please give us a call (307-288-1188) and we will be happy to help.

In conclusion

Automatic dosing systems are powering a new generation of hydroponic growers around the world.

If you would like to learn how automated dosing systems can save labor and boost your bottom line, see our recorded auto dosing webinarThe webinar was hosted in partnership with Autogrow, a recognized leader in hydroponic production.

 Want more information on auto-dosing? Check out our free download: Automated Dosing Webinar Most Asked Questions.

 

Read more: 7 Common Questions About Auto-dosing in Hydroponics

Topics: Hydroponics

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