Thread tape on the nippld threads.
tehehehe nipple threads
In all seriousness, you'll get much better results with 2 people.
Do this
Crack Nipple
Helper pushes pedal 2/3 or travel
Close Nipple
Release pedal
Top up fluid
Rinse
Repeat
The
pump/pump
"crack it"...
"let got"
close nipple
technique doesn't work too well with this system