I use a 200 gallon with a 22 fot boom. works great. One critical thing is to clean and put light oil or antifreeze in the pump each time if you are using a rorary pump. It will extend the life of the pump 3-4 times. Some of the chemicals are agressive and will casue pitting and destroy the rollers. If you need the cacluations for nossel size, hight of nossel from the ground and speed over the gound let me know, I will be happy to give them to you.
Dane