An indoor automatic watering system makes managing your cannabis grow easier and more efficient. Setting up an automatic watering system for your grow tent or grow room is not as difficult as you might think. It requires no special skills and all the information you need is right here. There are expensive kits available, but it is just as easy and far cheaper to purchase the things you need and put it together following the instructions below.
The automatic watering system that I describe is designed to allow you to water multiple times per day without supervision. Below you will find complete plans for a DIY Automatic Drip System for your grow tent. We also have plans for DIY Self-Draining Saucers and a DIY Auto-Pumping Drain Bucket to remove water from the tent. Together these three components create an effective, reliable, reasonably priced and easily set-up automatic watering system for indoor cannabis.
In this guide, I cover setting up the drip system. I include the components that you need along with assembly and installation instructions. I also cover the siphon effect problem that will limit the height that the water can be in your reservoir tank. This guide includes all the information you need to set-up and install your indoor automatic watering system for your grow room or grow tent.
Once you get the system in place, there are several keys to managing it properly. Be sure to read our "Guide to Automatic Watering for Indoor Cannabis”. We also have several articles and tutorials to help you feed and water your cannabis plants like a pro. Be sure to read “Principles of Fertigation” and “How to Water Cannabis in Coco” to get started.
DIY Automatic Watering System Overview
An Automatic Watering system begins with a reservoir, which should sit outside the tent or grow space. A pump sits in the reservoir and runs on a timer. The pump delivers water through one main waterline into the tent, where it is distributed to the plants using Hydro Halos or drip emitters.
My pots sit on plant elevators in “Self-Draining Saucers”, which empty to my “Automatic Pumping Drain Bucket”. The automatic pumping drain bucket resolves the problem with collecting run-off and prevents you from having to raise your pots within the tent. It automatically moves the run-off water from the tent to a separate bucket which sits outside the tent, next to the reservoir. This is a complete and reliable automatic watering system that any grower can assemble.
Automatic Drip System Components
Everything you need to put together the drip system for your indoor automatic watering system is listed below. These are the components that I purchased and use in my own system.
When selecting a bucket, barrel, tank, or tub for your reservoir there are a few things to consider.
Size: You want a reservoir that will hold enough water to run your system for at least a day or two. In a 4x4 tent I can use up to 3 gallons per day.
Height: Tall reservoirs allow you to use fountain style aeration. However the siphon effect problem may limit how much water you can fill in a tall reservoir.
Color: The reservoir should protect the nutrient solution from light as much as possible. Avoid clear plastic or white containers that allow light to penetrate.
14-Gallon Plastic Drum
The pump that you need for an indoor watering system is not very large. It needs to be powerful enough to raise the water into the tent and provide some pressure to ensure equal distribution. However that task can be handled by pretty small pumps. About 300 GPH should be the minimum for any auto-watering system. If you have a large grow you can estimate about 60 gph per plant to determine how large your pump should be.
We recommend running one pump for up to 8-10 plants. Running more than 10 plants on a single pump makes it extremely difficult to balance the distribution of water among the plants. If you are growing more than 10 plants, you should set up two systems with separate pumps.
400 Gallon Submersible Pump
A good timer is important, but there are some over-priced cycle timers that are actually less convenient to use. I recommend a good digital 24 hour timer. It should allow you to set multiple events per day and control the timing and spacing of each event.
Digital Timer with one second intervals
When you keep nutrient solution in a reservoir it is important to keep the water oxygenated. Water with a high level of Dissolved Oxygen helps to prevent bad bacteria and is great for the plants. For small tanks, up to about 30 gallons, air-pumps and air-stones provide adequate oxygenation. If you are run a larger reservoir or use organic nutrients then you should use a stirring pump to mix and oxygenate the solution. A stirring pump is a small fountain pump which should sit in the reservoir and run periodically to “stir” the nutrient solution.
Air Stone and Tubing
It is best to keep the temperature of the water in the reservoir between 65-68f (18-20c). This temperature range helps to maintain dissolved oxygen and prevent infestation with anaerobic bacteria. Read more in our guide, “Guide to Automatic Watering for Indoor Cannabis”.
Main Water Line
This water line attaches to the pump in the reservoir and runs into the tent. I prefer “poly tubing” over “vinyl tubing” for the main water line. Poly tubing is a semi rigid tubing that bends gently and resists being crushed. When using the drip emitter system, you need to use this Poly tubing. With the Hydro Halo system, you could technically get away with using vinyl tubing for this task, however poly tubing is a much better option.
1/2 inch Black Poly Tubing
I have used two different systems for distributing water to the plants. My first indoor system used feeder lines and drip emitters. I recently switched to using Hydro Halos. Both systems work well but have different advantages and disadvantages.
Hydro Halos offer superior water distribution. I can go weeks without hand-watering the plants because the distribution of water does not leave any dry spots within the media. The drawback to Hydro Halos is that they really can only be used in final containers – leaving you to hand-water all through the first several weeks.
Drip Emitters offer much more flexibility. You can put just one in a seedling pot and then add more as the pots and plants get bigger. The drawback is that you will end up with a lot of water lines running around and it can be difficult to set enough emitters in large pots to get good saturation.
Hydro Halo System
I think that the Bloom Brother’s Hydro Halos are the perfect option for a DIY drip system for indoor cannabis. They have greatly improved the distribution of water in my system from the dripper lines that I used to run. This can reduce or even eliminate the need for periodic hand-watering. They are also easy to use with Ball Valves to control the flow to individual plants.
6" Hydro Halos
½” Vinyl Tubing
Drip Emitter System
The drip emitter system offers more flexibility than halos. However, they do not distribute the water as effectively. If you set up a drip emitter system you should plan to hand-water at least once per week to flush out salts that can accumulate in the regions of the pot that don’t get well saturated by the drippers.