I meant to reference, in the videio, my video about well water and the need for filtration. If you are using dirty water (well/pond/lake/river/stream) for your irrigation you NEED to watch that video linked here: ru-vid.com/video/%D0%B2%D0%B8%D0%B4%D0%B5%D0%BE-zaN92HuFphw.html
Irrigation system with multiple stations and you got one with not a lot of pressure you could have simply walked around and turned off the heads to build up pressure you will find those leaks and make necessary repairs should never have to cut the backflow out and if you don't find any leaks then you work your way to the next which would be the control valve not the backflow now the homeowner has a 500 to $800 repair because you removed their backflow good job.