For those of you who use the Little Giant waterer: How do you adjust the valve so it knows when to shut off? I just installed two of them and had to turn the water pressure way down low. One of the bowls overflowed when the pressure was higher. I read somewhere that you can adjust it to stop at a certain point. Is that true? Should the water pressure be higher? These things are exactly cheap and I don't want another waterer that will overflow and make a muddy mess.