Dosatron Injector

I recently purchased a Dosatron D14MZ2 fertilizer injector from BFG Supply (in Joliet, IL) and thought I would give some idea of how it works.

My reasoning for the purchase was to allow us to provide a constant feed to our plants in and around the greenhouses at a low rate (50ppm N). Prior to the injector I was either hand mixing Neptun's Harvest fish emulsion (FE) in a watering can or using a Miracle Grow LiquaFeed Ready-To-Use hand sprayer. The advantage of the fish emulsion is the fact that it's all organic and is almost impossible to burn the plants with. The Miracle Grow provided a higher rate of feeding over the FE but can run the risk of phytotoxicity. The single largest downside to either option at a larger scale is cost. In order to feed the amount of plants we have I was using 2 Miracle Grow fertilizer cartridges a week and up to 2 FE bottles a month. Here in Chicago that came to $25 per week in April I was spendnig on fertilizer. Add to that the labor to hand mix the FE in 2 gallon amounts and we were spending almost $150 a month!

Now, I did a ton of research into injectors prior to the purchase and one thing I found was that some fertilizers "tank mix" better than others so I first had to find that. I researched and tested concentrates from Scotts, Peters and Daniel's. In the end, the Daniel's 10-4-3 proved to be the safest and most cost effective option. Like the fish emulsion it's organic so fertilizer burn is lowered if not removed completely. Additionally, the Nitrogen in the mix is of a form that plants can uptake more efficiently. From my supplier here, BFG, a 4.7 gallon jug of Daniel's is around $34.

I decided on the Dosatron injector over the others because they use fewer parts in the unit. Not only are there fewer parts, less of them move. Fewer moving parts means fewer breakdowns long term. In addition to that, when I had questions prior to purchasing the unit their customer service was grade A. Despite the fact that I'm a small grower and only needed a single injector they took the time to answer every question I had and provided all sorts of tips on how to size the unit. In the end I decided on their newer 14GPM unit since I was powering a single hose, wanted an easy bypass and wanted to make the unit portable.

I purchased the unit from BFG for $285 along with a $26 filter. Additionally, I purchased the bypass kit directly from Dosatron as BFG didn't carry it. I also purchased a back flow valve from a local Menard's as well as some hose menders, plumbing tape, 600lb moving cart/truck, some 1/2" plywood, a 5 gallon bucket and 4 "U" bolts. Total cost for the entire unit was $422.

For the bypass there are 2 options: build a PVC one or purchase one directly from Dosatron. I opted for the Dosatron bypass since the unit is going to be portable. If it was wall mounted directly I would have built a bypass out of 3/4" PVC with unions so it could be removed for maintenance. The inline bypass took about 15 minutes to install. The only downside is you have to remove the air bleed valve to install it. The service rep at Dosatron told me that they unit could have been ordered with the bypass installed through BFG to save me the work. I should note that BFG never told me that. However, even if they did I didn't want to wait 2 weeks to get the system in, they had the standard one in stock.

It took perhaps an hour to build and assemble the entire unit, the injector itself was extremely simple to setup, perhaps 10 minutes. I can't stress enough how easy the injector is to install and operate, Dosatron has done a great job on that part. Once assembled all I needed to do was determine how to mix the fertilizer. Here's where Dosatron's service and support excels. I called them to see if they had any recommendations, not only did they help, it turns out they have a calculator on their website to give you the rates and settings you need for a particular feeding rate.

In the end I calculated that I need 4 cups of Daniel's concentrate to 5 gallons of water and the injector set to 1% to achieve a final rate of 50ppm N. This provides us with a low, slow constant feed for all the plants.

Also, since we have kids around I wanted to be sure they don't drink from the fertilized water even if the bypass is on. So, I installed a "Y" valve on the spigot, one side goes to the injector, the other has a regular hose on it. Additionally, I used black hoses on the injector so the kids know not to use it. Black = bad, green = good.

I'm using a 5 gallon bucket a week of the concentrate which equates to 1 gallon of Daniel's per month. At that rate the 4.7 gallon will last me almost 5 months! This comes to around $6.80 per month in fertilizer now which means I'm saving around $143 per month. Seriously, you can't ask for better than a 3 month ROI.

Images of the injector and setup are here.