Clogged sprinkler Heads

I have a well, a centrifugal pump, an Intermatic timer, and an old cast metal K-Rain 4 zone indexing valve with one zone closed off. I replaced the indexing valve interior parts maybe 1-2 years ago. I will list the symptoms in the order of their occurrence. Can you tell me the most likely cause and recommend a solution?

1) Several months ago, several mist heads became clogged with rotten, black, vegetative matter, leaves, etc. Most located at end of zone lines. Just found another head totally clogged with large clump of same stuff.

2) Reduced coverage from existing sprinkler heads. Also possible reduced pressure although haven't measured it.

3) After indexing flow valve, one of the 3 zones (call it zone A) operates by itself as it should. When I index to the next zone (B), zones B and C run at the same time. When I index to C, it runs by itself as it should.

Can you tell me the most likely cause(s) and recommend solution(s) ?
Bruce

Hi Bruce,

What is the water source for your pump? From the problems you are experiencing I'm going to assume that it is not a well, but a pond or stream. If my assumption is correct the most likely culprit is the intake line from the pump. A malfunctioning foot valve or intake screen can cause a lot of irrigation pump problems.

I would replace the screen, and either place it on a block, or use one of those floating decoy ducks, to make certain that the screen is not laying on the bottom of the pond.

After dealing with the intake pipe, you will need to flush the sprinkler system, and probably clean and rebuild the sticking indexing valve.