Hey all. I've recently installed a nice big rain collection system, and have run into a small issue I hope to solve easily.

Basically, the rain barrel is connected to a pump that in turn feeds a hose manifold, and I have a bunch of hoses that go to various gardens.

The problem is that the rain barrel is located at a point higher than the gardens, and I'm getting gravity flow-through when the pump is off. When I look at anti-siphon valves, they are (apparently) not what I need - they are for preventing backflow into the water supply, I want to prevent low-flow forward into the system, which drains the tank, floods the garden and so on.

I've looked at check valves with adjustable cracking pressure, that's not quite what I need. Can someone tell me what to search for? I want a valve that only opens when the inward pressure is above 2 or 3 psi (ideally adjustable).

What is that thing I need called?