CAN THE SPRAYER BE USED WITH ANY SPRAYABLE LIQUID, LIKE INSECTICIDE OR PESTICIDES, WEED KILLER,ETC.?

My parcel is 2 acres. I am surrounded by vacant undeveloped land where the gophers breed unrestricted. My property is under constant invasion of gophers and they travel through a freeway network of existing tunnels. I am in Southern California/San Diego county.
My personal experience:
1)Trees which tolerate gopher activity: olive, macadamia, citrus.
2)Trees which the gophers crave and will eat and kill: avocado, plum, apple, pecan, banana.
I used to trap gophers. Averaging 3 gophers a day during spring time. I would trap with the wire Macabee traps and the black plastic Black Hole traps. Usually 12 traps in use. I prefer using the Black Hole since it is much easier to setup and use. I would spend about 1 hour a day between setting and checking traps in the morning and evening. Some times my dogs would check the traps for me, yay! doggy favorites.
Now I poison the gophers, using the probe and crank machine like what You sell. I use Gopher Getter poisoned seeds, little round black seeds that smell like black licorice. The little round seeds don't plug my probe nearly as much as Last Bite pellets. The pellets would jam almost daily so I stopped using them and now only use the seeds, even though they are alot more expensive.
Now I spend about 20 minutes twice a week checking my property for gopher activity and administering the poisoned seeds. I still see my dogs digging up and eating the gophers but the poison level in the dead gophers must be low enough that it does not affect my medium sized dogs.
I wil be trying out the noise makers. Either the battery powered ones or the windmills and see how effective they are. I used to have geese ( until the coyotes killed all 10 of them) and I don't recall having such a huge gopher problem when the geese were here. But that was before I tried growing fruit trees so maybe the gophers did not bother me then. I will have to get more geese and test out that theory. But first I'll have to "coyote proof" my fences. Maybe the geese made enough noise that the gophers stayed away or maybe the geese were such mean aggressive birds and there was always one of 'em awake that they killed any gophers that popped out of the ground. I miss my geese, they also kept everything mowed and trimmed perfectly so gophers had no place to hide either. Horses and goats don't seem to deter gophers at all.
I tried smoking the gophers out. Not effective at all. Lots of fun but did not work.