You need to be really careful when you mix parts from different manufacturers because the threads and diameters can be incompatible. Pickup any two unions from different companies and odds are they will be visibly different.
Is the leak coming from the threads or the actual connection between the PVC and the black coupler of the pump?
Post a pic if you can.
jared, i tried to email you the pic this morning? not sure if went through or not. the fittings were 9- shipped from reeflo, so i ordered them but it i can rectify before they come that would be great