@vmstretch, thanks for reaching out. Sorry to hear you’re confused on creating a custom nozzle. Drip zones are a bit tricky.
Assuming you have 1 bubbler per tree that outputs 1 GPM and it covers a 3 foot circle, I’ll assume the following:
The radius (r) of the circle is 1.5 ft. Where r is the radius and Pi is the mathematical constant; r2*Pi = area of a circle. Therefore the area of your circle must be 7.069 sq feet = 7 sq ft rounded.
Next, we take the PR equation: PR = (96.25(A*B))/(C)
A = #heads -or- #emitters = 1
B = flow rate (GPM) per head -or- emitter = 1
C = zone square footage = 7
= (96.25(1*1))/(7) = 13.75 Inches per hour
Are you sure the emitter puts out 1 gallon per minute? i.e. can it fill a 1 gallon milk jug in one minute? If so, then this number sounds correct. However, if the emitter only outputs 1 gallon per hour, then the output is only 0.228
A = #heads -or- #emitters = 1
B = flow rate (GPM) per head -or- emitter = 1/60 = .0166