I've installed a fertigation system in my greenhouse. In its current state the system looks like this:

inlet (60 PSI) -------à
injector----------- (37 PSI) à sprinkler valve
-------à 10PSI regulator----------
Driptape

A difference in pressure between the inlet and the outlet of about 25 should be sufficient to generate enough suction at the injector to pull the fertilizer mixture into the irrigation flow. Obviously I only have a difference of 23. I suspect the problem is that the PSI regulators on the end of each sprinkler valve are keeping the outlet pressure too high by not allowing enough flow to the drip tape. The drip tape can handle no more than 15 PSI. I think changing the 10PSI regulators to 15 PSI regulators would give me the additional flow needed to decrease the outlet pressure but I'm very new to this stuff and would appreciate any input. Thanks!