just added 4 zones to a lake pump system. my problem is while any zone is running the pressure is surging. the system consist of 1 1/2 suction running about 45 feet to pump. when lake is full the elevation change is only like4 feet max. right now the lake is almost 4 feet down. the pump is a 2 horse meyers with a 1 1/2 main running no more than 35 to 40 feet to the furthest valve (1 inch valves and laterals).... zone 1 consist of 13 rainbird 1804's (2 of them have 15' van at 360, and the other 10 are 15 vans at 210 degrees) This is a landscape redesign and the landscaper could have possibly damaged the main today with shovels. I thought it may have been a busted lateral but 2 new zones are performing this way. Is there anything that can happen to a pump to make it perform like this. when this surge is at it best pressure the heads are performing great but the low end of the surge the heads will start going down a little also.