Ppm ready to flower ?

I have three white widow strains that I am ready to flip. I give them all the same amount of nutrients and one plant has runoff at 1250 PPM. One has around 1000, and the other surprisingly was 650. What to do . Add some more nutrients to the 650 ??? I also started adding molasses for the soil.

Don't read soil runoff, I work on a full or half strength feed when the plants need. In soil runoff is not going to tell you what they want.