Situation: Recently bought a house that uses city water for the house and uses a well to supply irrigation. It worked fine for the first few months. We had some sediment that blocked the diaphragms. We put in a sediment filter which solved that problem.

We installed a Toro timer, which seemed to work fine.

Now, the problem I get is that when I manually turn on the sprinklers at their valve, I get full flow. When I use the timer box, I get full or mostly full flow (but noticeably less than when I manually turn them on...) and the flow slowly diminishes to a trickle.

I have a back-flow feature on the sediment filter which I can attach a hose to that has full pressure all the time. I have purged it to ensure the filter isn't clogged up. I also have a regular hose that also has full pressure all the time.

Any ideas what might cause this problem?