Dripper problem

Im trying to set up a dripper irrigation system.

Iv made a ring main around my greenhouse in 19mm supply pipe with 45x 4mm 1 meter length feed lines with adjustable drippers on the end.
Iv used a filter and non-return valve.
I'm using a 4000 ltr per hour pump the sicce multi 4000

the problem im having is not enough pressure at the drippers? im getting just enough pressure to lliterally "just drip"

i know all symptoms point to more powerfull pump needed but was pretty sure a 4000 would do the trick?

any ideas?

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