ok made some more changes to the block.
first i think the last one didnt have enough jet orifice area with the smaller tubes.
please correct me if i am wrong but here are my calculations
the tubes have an OD of 1/16 or 1.5875mm
the tubes have walls 0.014 inches thick or 0.355mm
giving a radius of 0.43875mm
so each jet had an area of 3.14*0.43875*0.43875 =0.6044mm2
with 42 tubes total area is 25.38mm2
on this new version i have increased the number of tubes to 48 giving a jet orifice area of 29.0112mm2
The tubes are 0.5mm from the cup base or 2mm into the cups.
some jet action from a 1000l/h pump with 1.3m max head
will post some results later.
i might not be able to refine this design much more as these tubes are the smallest ID i can get so far. I can get smaller OD with thinner walls but the ID is about the same.
i could try the smaller OD tubes with 2mm cups.