Introducing the Netafim NetBow
Container growers using artificial media (such as coco coir) or light natural media face a challenge when using drip irrigation. Light media does not move water laterally – drip irrigation supplies water to one point in the container, and that’s where it stays. This causes wet media directly under the dripper and dry media in the rest of the container. Since roots grow where the water is, the end result is nonuniform root growth and an unhealthy plant. Specific crops that face this challenge include container-grown cannabis and blueberries, since both need high water application uniformity and typically use artificial media.
The Netafim NetBow solves this problem by applying water in a ring around the entire container instead of a single point. It delivers the precision of drip irrigation with full-container water application. The NetBow works best in 5 to 10 gallon containers and will not work in a container smaller than 5 gallons due to its size.
How the NetBow Works
Each NetBow is a 10-inch diameter circular plastic frame that holds a small-diameter dripline. The internal dripline is based on Netafim’s clog-resistant Typhoon technology with an outlet every three inches. This provides ten drip points along the circumference of the ring when water is connected through a 1/8” barbed fitting. A 2” break in the ring allows the NetBow to be easily installed in or removed from the container, even if it holds an existing plant.
By itself the NetBow is not a pressure compensating device, however most growers combine it with a Netafim PCJ Barb Outlet Dripper, referred to as a “hub dripper”. If used without a hub dripper the NetBow outputs 4 gallons per hour when supplied with 15 psi of operating pressure (1/2 gallon per hour from each of the 8 internal drippers). If the pressure is higher or lower than 15 PSI, the output will be higher or lower than 4 gallons per hour. If used with a hub dripper, the output of the NetBow will be determined by the flow rate of the hub dripper up to 2 gallons per hour, and will not vary with pressure. For example, when used with a 1 gallon per hour hub dripper the NetBow will output 1 gallon per hour uniformly around the ring. Hub drippers greater than 2 gallons per hour should not be used.
The NetBow delivers its best performance when used with a Netafim PCJ hub dripper. In this configuration it becomes a pressure compensating device, meaning that all of your containers get the same amount of water even if there are pressure differences within your system. For example, on a long row water pressure at the beginning of the row may be higher than at the end, but the water output by each NetBow along the row will be constant.
How to Install the NetBow
Installing the NetBow is simple. Simply place it on the surface of the container around the plant, and use a length of Netafim Super-Flex 1/8” Tubing to connect it to your PE Supply Line. Each NetBow comes with five stakes which can optionally be plugged into the bottom of the ring to give it extra stability in the container.
If you use a hub dripper, one end of the Super-Flex Tubing plugs directly into the 1/8” barb on the Netbow and the other end plugs into the output barb on the hub dripper. The dripper can then be plugged directly into your Poly Hose supply line. Use a 3 mm Punch Tool to make a hole in the supply line.
If you are not using a hub dripper, instead plug the other end of the Super-Flex into the 1/8” barb of a ¼” x 1/8” Reducer Coupling. The ¼” barb can then be plugged into the PE Supply Tube using a 3 mm punch tool.
If you are not using a hub dripper you need to ensure that 15 psi pressure is applied to each NetBow to give the expected flow rate of 4 GPH per container. We recommend using a Senninger 15 PSI Pressure Regulator for this. Depending on your layout, you can use one pressure regulator per table, one per irrigation zone or one regulator at your pump for your entire operation. The pressure regulator will deliver 15 PSI for flow rates ranging between 2 and 20 gallons per minute, as long as the pressure upstream of the regulator is above 15 PSI. The 2 to 20 gallon per minute flow rate range translates to 30 to 300 containers supplied per pressure regulator when the NetBow is used. You also need to ensure that your Poly Hose supply lines and other system components are large enough that there will not be significant pressure drops from the first to the last plant in each row.
If you use a hub dripper pressure control is simpler. For the hub dripper to work properly pressure should be anywhere between 15 and 60 psi. If you know your water pressure is within this range you are ready to go. If your water pressure is above 60 psi we recommend using a Senninger 35 PSI Pressure Regulator to get it into the right range. Assuming a 2 GPH hub dripper, one pressure regulator can supply between 60 and 600 containers.
The number of NetBows you can run simultaneously may be limited by your water supply. If you know the capacity of your water supply it is simple math to determine the maximum number of containers you can irrigate at once. For example if your water supply is capable of 10 gallons per minute, you have 10 x 60 = 600 gallons per hour available. If you use a 2 GPH hub dripper you can run up to 300 containers simultaneously.
Another important water supply consideration is water quality. As with any drip system, the NetBows and the hub drippers have small passageways within them that can become clogged if water is not clean. We recommend using at least 120 mesh filtration to prevent clogging. See Irritec Screen and Disc Filters.
Schedule your irrigation by using your irrigation cycle duration and the application rate of your NetBow to apply the right amount of water to each plant. For example, if you use a 2 GPH hub dripper you know each plant receives 2 gallons for each hour you irrigate. If you would like to apply one gallon with each irrigation cycle, set your duration to 30 minutes.
Many growers using light media prefer to irrigate several times per day, a practice known as “high frequency irrigation”. If you use a hub dripper with the NetBow high frequency irrigation is no problem. The Netafim PCJ hub dripper is a “non-leak” dripper, which means that when pressure in your supply line is below 10 psi it shuts off. The result is that when you turn your water supply on all NetBows begin dripping simultaneously and when you turn it off they all shut off at the same time. This ensures that each container has the water running for exactly the same amount of time as the others – an important feature when irrigation cycles are very short.