Run off ppms

I measured the ppms in my run off and it is lower than nute water. And the plant looks healthy. Anyone have this?

I don't measure that I have a soil ph meter and I just keep my veg feed around 600 ppm and my full flower feed I goto 1000 maybe 1150

I dont think that I am going to be checking run off anymore. My ppms are around 600 in flower. Tried higher but got slight nute burn. Probably the strain. 5 weeks veg and 4 weeks flower.