You will not do damage to the pump UNLESS you cut off all the water flow for many minutes. Most pumps will not suffer any damage from no flow unless they have no flow for 10+ min. Just cut down your supply at the pump. If a well pump only pumps 1/4 gallon of water an hour it can't overheat so don't worry about the pump so much. When your done watering just turn off the pump.

Good luck,
Tom

Thanks Tom for the information. I will give that a try. With less pressure, I should be able to use the aluminum diffuser that I have without doing any damage to it. I just wasn't sure how long you could run the pump without doing harm.

I appreceited your response.

Larry

Here is how pumps work that most people don't understand. Pumps don't hurt to run without flow BUT they do (through friction) heat the water. This friction will boil the water in 15-30 min in most pumps. Some pumps (such as a modern Goulds pump) resist this boiling by internal design but are not perfect. Basically if you run your pump without flow for a few min your fine. That being said even a tiny flow will not allow the pump friction to boil the water. Simply a tiny flow will stop the boil. So if you are going to reduce the flow it will never hurt the pump. Don't know what aluminum diffuser you are using but I would say you are fine and will not damage it. A 1hp pump is not that strong really. Most likely it is a sprinkler pump and the max pressure is only in the +-55PSI range. You will be fine.

Good luck,
Tom