poor atomization below 20% duty cycle

[turboii]

i am new to water injection, and i just finished installing and testing my HFS-3 system in to an FD3S and i have a couple questions. I am controlling it with a PWM output from a haltech PS1k, with can be fully mapped 0-100% duty from an rpm vs boost table. Nozzle size is 1mm, and i am just spraying straight water.

What is the best switching frequency to use?

also, I had the nozzle set to spay into the air, and noticed poor atomization below 20% duty cycle. in fact, nothing would even come out below 16%, even though the pump starts running at 12% with the threshold turned all the way down. I tried several different frequencies, from 30 Hz up to 200 Hz, and didnt have much effect on results

so why the poor atomization at low duty cycle? when i tested it, i used the full run of smaller hose (FAV to nozzle) that came with the kit, would a long hose run cause it? I would think with something operating at over three times the pressure of a fuel injector would be a little more precise?