They work great - as long as you get a decent one.
Many work by injecting water into the canister, thereby forcing the fertilizer or pesticide into the spray stream. Because of that design, the concentration changes with time, becoming more- and more-dilute; not a good thing.
A better one will use a siphon mechanism instead, maintaining a constant concentration throughout the application. Even with that, however, the mixing ratio can change, depending upon your water pressure and flow rate. I suggest the following "calibration" methodology:
- Set it up as you intend to use it - specific hose and spigot.
- Fill the canister with a known volume of water containing food coloring (to make it easier to see).
- Place the sprayer so its output goes into a bucket of known volume (typically a 5-gallon one is used here in the US), and turn on the water.
- Keep track of the amount of output collected (it pays to have 2 buckets, so you can dump one while the other fills) until the canister is empty.
From that you can calculate the mixing ratio - for example, if one liter of "concentrate" produced 20 liters of spray, from that point forth, you can simply mix up your concentrate at 20x your desired final concentration, and you're good to go!
Such a procedure is also good for "Hozon" proportioners, which even though they are rated at having a 1:16 ratio, I have seen go anywhere from 1:20 to 1:12.
Hose End Sprayer
Linear Mode
