Fertilizer must be in liquid form when it’s poured into the Add-It® and Fertilizer Caddy® fertilizer injector. If using a premixed liquid, you can pour it in full strength. If using dry, totally water soluble granular fertilizer, such as Scott's Miracle Gro®, Peters Professional®, Bandini Pro Choice®, or Grow More® premix with water at a ratio of 1 pound of dry formula to 1 gallon of water. Fish emulsion can only be used in the injector if it has been premixed with water at a 1 to 1 ratio. We strongly discourage the use of any petroleum based additive in the injector Read and follow the directions printed on the container of fertilizer. Usually, 1 gallon of liquid fertilizer will cover 1,000 square feet. Apply Teflon tape to the male pipe threads before inserting them into the dispenser for installation. Usually 2 to 3 wraps will be sufficient. Hand tighten the male pipe thread fittings when installing the injector, except for the last full turn, when you may use a wrench or pliers for an additional half turn. Be careful not to over tighten.

To fill the fertilizer injector, remove the top fill cap. Insert a fill funnel into the opening and pour in liquid solution. Fill the unit completely. Replace the cap and the fertilizer injector is ready for operation. Turn on the irrigation system. Consult chart on back to determine how many gallons of water passing through the irrigation system it will take to empty the Fertilizer Caddy® fertilizer injector completely. For example, let’s say that you’ve installed the Model GMPC 75100 and the irrigation system is operating at a flow rate of 3 gallons per minute. Knowing that it takes 200 gallons of water to empty the injector, divide this number by the flow rate of 3 GPM. You now know that it will take you a little over an hour, or 67 minutes, to not only water your trees and shrubs, but also fertilize them.

To refill the fertilizer injector before you have completed watering, simply turn off the water by closing the control valve, and remove both the drain cap on the bottom and the fill cap on the top. Allow all of the water to drain from the tank, and replace the bottom drain cap. Place the fill funnel in the top fill opening and refill the injector. Replace cap and turn the irrigation system back on. Once you have completed watering, there is no need to drain the fertilizer tank, unless you want to refill it to have it ready for your next irrigation cycle. It will not harm the unit to have water running through it when you are not fertilizing. On the contrary, the clear water passing through the injector will help keep it clean.

Fertilize as recommended during the growing season. During the winter months, if there is a possibility of freezing in your area, it is highly recommended that the tank be left drained and vented to atmosphere. You might also consider covering the tank to further protect it from the elements. Painting the unit with a water-based acrylic latex paint will also add to the longevity of the unit, especially if it is exposed directly to the elements. The fertilizer injector should be installed on a level surface and not in direct sunlight.