Irrigation pump tank outlet size

I've got a shallow well and a 1HP pump putting out about 10-12 GPM for irrigation only. The pump discharges thru a 1" line but I currently have 1 gallon pressure tank connected which uses a 3/4" line. I want to keep my gpm and pressure up as high as possible so should I find a larger tank that uses a 1" opening, since that's what I'd like to run for the sprinklers?

Pumps make GPM and pressure, not the tank. All the tank does is reduce the number of times the pump cycles on and off. A 1 gallon tank only holds about 1/4 of a gallon of water. Your pump is going to cycle like crazy. You either need a much larger tank or a Cyle Stop Valve.

Thanks valveman, but I don't think I explained my situation well (no pun intended). For irrigation I've always used a small, pre-charged tank connected to the pump. I don't think the idea of the small tank is to store water, but to add some needed pressure until the pump catches up. In the past my pump has never cycled, instead it comes on when water is needed, and runs until you turn the water off. Here's a photo of the setup I used at our old house. My question is whether it makes a difference if the outlet on my pump is 1" but then I bushing it down to 3/4" connect it to the 3/4" precharged tank, then go back to a 1" main line run to the sprinklers. Basically I want to use every drop of water that pump can put out, that way I can run more sprinklers at the same time. So by going down to 3/4 to accommodate the pre-charged tank, aren't I shooting myself in the foot so to speak???

The tank stores about 1/2 gallon of water and a few pounds of pressure. That's it. Then it's up to the pump, the tank has nothing to do with running the sprinklers. If you didn't have a pressure switch, you wouldn't need the tank.

bob...