Automatic Watering Systems for Indoor Cannabis
This article is your go-to guide for setting up and using an automatic watering system for your indoor cannabis cultivation. We will guide you through the best types of automatic watering systems, particularly focusing on the addition of fertilizers to your irrigation water, known as fertigation. Plus, we’ll chat about why it’s essential to feed your plants right to prevent nutrient issues.
Automatic watering systems can sometimes have trouble with bacteria, so we’ll share some tips on keeping your hydroponic reservoir clean and bacteria-free. We’ll also cover how to maintain your reservoir, control how much water you use, and decide when and how often to feed your cannabis plants.
Switching to an automatic watering system can be a game-changer for your fertigation process. Whether you follow our “Automatic Watering System” plans or do things your way, our advice in this article will help you dodge common problems and make the most of automating your plant watering for your cannabis crop.
What is the Best Automatic Watering System for Cannabis?
The short answer is that it depends. There are numerous types of automatic or self-watering systems available to choose from, we will focus on the two that are most commonly used by cannabis growers. At a high level they can be classified as top-feed and bottom-feed. These categories have multiple sub-categories. For example, there is Top-Feed Drain-to-Waste and Top-Feed Recirculating. It is crucial to understand the method of irrigation or feeding you are employing in order to select the appropriate automatic watering system for your specific growing needs.
Top-Feed or Bottom-Feed Irrigation Systems?
For automatic feeding, you need to choose either a top-feed or bottom-feed system. The bottom-feed system floods the containers from underneath and primarily distributes water through the media using capillary pressure (wicking). However, bottom-feed systems often provide sub-optimal water distribution due to reliance on wicking. Additionally, without water running down through the media, salts can accumulate, leading to nutrient burn. Also, if you are using a bottom-feed system with a drain-to-waste setup the system will waste a greater amount of nutrients.
Use Top-Feed Irrigation Systems for Cannabis Feeding
When it comes to feeding your cannabis plants, top-feed irrigation systems are the optimal pick. A top-feed system introduces water from the top and allows it to naturally flow through the growing medium, resembling the natural flow of rainwater in the environment. I am a firm believer in trying to make as much of the indoor processes as possible mimic the natural environment. A top feed setup provides you with the ability to regulate the amount of water you apply, and it even allows for runoff to occur during each fertigation event which provides a wealth of information on how your grow is performing. We will cover this topic in a future articale.
As discussed in our article, “Cannabis Feeding Fundamentals” run-off plays a crucial role in removing excess salts and preventing nutrient burn. During each feeding, approximately 20% of the nutrient solution you apply should flow through the container and result in run-off. This cannot be accomplished with a bottom-feed irrigation system. Due to the benefits of run-off, we recommend top-feed irrigation systems for feeding cannabis. Plans for a top-feed irrigation system can be found in our “Automatic Watering System” tutorial.
Recirculation or Drain to Waste?
In a recirculation system, nutrient solution is continuously reused and circulated to the plants multiple times a day. On the other hand, a Drain to Waste system utilizes nutrient solution only once, and any run-off is discarded as waste rather than being recirculated for reuse. While Drain to Waste may seem wasteful, it offers several advantages, especially in media like coco.
The Drain to Waste feeding setup ensures a more consistent nutrient solution for the plants. As explained in our tutorial, “How to Mix Nutrients for Cannabis”, a well-balanced nutrient solution encompasses factors such as the appropriate electrical conductivity (EC), Nutrient Element Ratio (NER), and pH. When we initially mix fresh nutrients, we can set each of these parameters to the ideal levels. However, as the nutrient solution interacts with the plant, media, and environment, the EC, NER, and pH will naturally change. Consequently, the solution is no longer in its optimal state once it has been used.
Using a “Drain to Waste” feeding system ensures a steady nutrient supply for your plants. In our guide, “How to Mix Nutrients for Cannabis,” we explain the importance of having a well-balanced nutrient solution, considering factors like electrical conductivity (EC), Nutrient Element Ratio (NER), and pH. When we first prepare fresh nutrients, we can set these parameters to their ideal levels. However, as the nutrient solution interacts with the plants, growing medium, and environment, the EC, NER, and pH will naturally shift. Consequently, once the solution has been used, it’s no longer in its optimal state.
Recirculation systems are well-suited for deep water culture setups. In a recirculating deep water culture system, there is no media other than the water itself, and the system is generally sealed to minimize evaporation, except through the plants. Although the nutrient solution will still experience changes over time, these fluctuations can be managed within the recirculating system.
Use Drain to Waste Irrigation
Recirculation systems aren’t a good match for media like coco. The way the nutrient solution interacts with coco creates a less than ideal situation for ongoing use. Specifically, when it comes to coco, recirculation systems bring about some challenges. Coco tends to absorb calcium and magnesium from the nutrient solution and replace them with potassium. Reusing this nutrient solution will result in insufficient calcium and magnesium levels and an excess of potassium. This potassium overload can actually hinder the uptake of the remaining calcium, leading to rapid plant deterioration. Furthermore, as the nutrient solution passes through coco, its pH tends to fluctuate, making it tricky to maintain a stable pH in a recirculation reservoir.
On the other hand, drain-to-waste systems circumvent these issues and provide plants with a perfectly balanced nutrient solution every time. The drawback of drain-to-waste is the generation of waste water. Fortunately, with the use of automatic watering systems, you can fine-tune water delivery and reduce the amount of run-off produced. However, it is important that some run-off still be generated. To achieve full automation, an automatic drainage system is required in addition to an automatic watering system. In our “Automatic Watering System” tutorial we provide plans for an effective drainage system.
You should take responsibility to use or dispose of waste properly. The best use for hydroponic waste is to feed it to other potted plants.
Managing Automatic Watering Distribution:
Managing the distribution of nutrient solution in automatic watering systems is crucial to prevent salt build-up and ensure optimal plant health. As mentioned earlier, two important practices are applying nutrient solution until run-off and saturating the entire volume of the media during each feeding.
When handfeeding, nutrient solution distribution is typically not a concern. However, with drip irrigation systems that target specific areas, there is a risk of run-off occurring without complete saturation of the media. Water may flow through well-established channels, leading to run-off in the saucer while leaving certain regions of the media dry. In such cases, the run-off EC may appear low, but the water available to the plant can have elevated salt concentrations in the drier regions. If a plant shows signs of nutrient burn despite low run-off EC, it indicates a nutrient solution distribution problem.
To manage water distribution effectively in automatic watering systems, consider the devices used to deliver water and the containers in which you are growing. Using a wetting agent can improve the suitability of the water for automatic watering. Additionally, it is beneficial to periodically hand-feed the plants, ensuring complete saturation of the media. This practice helps to address any potential unevenness in water distribution and maintain optimal growing conditions.
Water Distribution Options: Drippers and Halos
Good nutrient solution distribution starts with the devices that you use to actually deliver the nutrient solution to the plants. There are many options. Our “Automatic Watering System” tutorial describes two different options for nutrient solution distribution.
Drip Emitters: One option we suggest is using drip emitters commonly found in outdoor drip irrigation systems. The advantage here is that the components are readily available, and the system is easily expandable. However, there’s a potential drawback – the distribution may not be ideal. Most indoor drip systems operate at lower water pressure compared to regular water supplies. Drip emitters, on the other hand, are designed for outdoor use with normal (full) water pressure. Their labels often depict them spraying water around, but in indoor systems, they may just leak instead. If they are adjustable, you can control the rate of leakage, but they might not effectively distribute the nutrient solution. To ensure proper distribution, it’s advisable to use at least four drippers per pot, evenly positioned around the surface of the growing medium.
Hydro Halos: The other option that we describe is for Hydro Halos. Until recently these were expensive, but they have become far more affordable. I switched from a drip emitter system to hydro halos and have been impressed with how much they have improved the distribution. I have been able to go several weeks without hand-watering and the plants remain vigorous and healthy. In my opinion, Hydro Halos offer the best solution for distributing the water in indoor drip fertigation.
See Our Complete “Automatic Watering System” Tutorial
The Best Pots to Use with Automatic Watering
To ensure efficient water distribution, it’s important to consider the containers used for your plants in an automatic watering system. Factors such as container size, shape, and material play a significant role in maximizing the benefits of automatic watering.
Container size should be determined based on the type of media you are using. Unlike In soil, container size does not limit the overall plant size. In coco/perlite, container size does not restrict plant growth. Coco provides ample root space and a healthier root environment, allowing for smaller containers compared to soil. Smaller containers are easier to saturate during each feeding, and with automatic feeding, the need for more frequent feeding is not an issue. Prior to discovering the many benefits of coco we used soil as our media. with soil we used a 5-gallon pot. When we switched to using a coco/perlite mixture we found that we could get the same results in a 3-gallon fabric grow pot.
The shape of your container has an impact on how water is distributed. Tall and slender pots tend to work better than short and wide ones. When using top-feed irrigation, gravity plays a significant role in how water is spread. A taller and narrower pot makes it easier to saturate the surface, ensuring that water moves effectively throughout the entire container.
The material of your container also affects drainage and the health of your plant’s roots. Conventional plastic pots with drainage holes only at the bottom aren’t well-suited for frequent fertigation. Fabric pots, on the other hand, offer superior drainage and encourage healthier root systems. They are also a cost-effective choice.
In my opinion, the best pot to use with coco in an automatic watering system is a fabric pot. They provide excellent breathability and drainage. However, there is a product out there that we are beginning to hear great things about, Air-pots. The open design of these pots should provide even greater breathability. We are still in the process of testing this product and will post our findings when testing is completed.
3-Gallon Fabric Pot
Three-gallon fabric pots are a great option to use with coco. However, due to the breathable nature of these pots you will need to feed your plants often to keep the media from drying out.
5-Gallon Fabric Pot
If you don’t want to feed that often or you want to grow very large plants in coco, you can use these 5-gallon pots.
#3 Air-pot
We are still testing growing with these pots using coco with an automatic watering system. We will provide out findings in a future article.
#5 Air-Pot
Air-pots are a bit more expensive than fabric pots, but we are hoping they are worth it. If you want to grow giant plants, these #5 air-pots may be what you want.
For information on automatic feeding system see our related article:
“Maintaining the Hydroponic Reservoir in Your Automatic Feeding System”
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