Question
I recently started up my lawn system (Montana, so we start late) and found that some heads weren't switching streams. I replaced some couple of Maxi heads with other Maxis, but then changed out some with low-slow Minis. Now, I'm not getting good flows in any of my four stations.

40 psi at the turbo pump, that also powers my remote irrigation system, which gets good flows even when all outlets are on. So it appears the problem is within the Rainbird irrigation system.

Questions are: Does it matter if I mix MaxiPaw and Mini heads within a station? Could this be a valve issue within the master switch box? In switching heads, I cleaned our sand and gravel from a couple of heads, let the water run to flush them out, and then replaced the head. Could a rock have blocked the system?

Thanks for your assistance.  

Answer
Hey Ed, I hope this helps. Valves do go bad, and if the diaphram is worn out, the valve will not turn on fully. I doubt however, that all 4 valves would go bad at the same time. The first thing I would check, is that the main turn on valve for the system, is on fully. It could also be, like you questioned, something is in the main line running to the valves (rock, etc.) and is blocking the flow of water to the valve manifold. To check this, you would almost need to cut the mainline pipe, about a foot before it enters the manifold. Turn the water back on, and see what kind of flow you are getting from the main pipe. Usually if something gets stuck in the pipe, it normally gets hung up at a elbow or tee joint. Some systems also have a master valve, this is an automatic valve that is installed right past the main turn on valve for the system, and is turned on by the controller as each of the other valves is told to run. If something is not working right in this valve, then your volume(pressure) could be weak. As far as mixing heads,  normally the maxi paws are going to be  rated at between 3 to 5 gph(gallons per hour) and the mini paws between 2 to 4 gph you can mix them as long as the gph on each of the heads is the same in relation to how much area they are going to cover. I would be a little concerned why you are getting sand in the system. This could indicate a break in a line, or if your pump is sucking in sand. Let me know if I can help you anymore. Good luck and have a great day.