Run off pH is crazy low

Growing in 2gallon plastic pot
Using Coast of Maine soil
Using Botanicare cal-mag, Veg and Flowering nutrients
50w led grow light

So I'm having a slight deficiency going into week 3 of flower, think I just under fed going into the transition from veg to flower and it's starting to show now. So today I gave her another good dose of flowering nutrients and figured I check the pH runoff to make sure that was in check... Well it came out reading 2.7-2.8 which I have never had it get so drastically low before. I water between 6.4-6.6 every time I water and my ppms coming out are in the 900-1000 range so I really don't know why my run off is so low. Any ideas?

Yeah that's crazy low all right. Did you try inputting fluids at a higher PH to see if it raised the number in the wash?

Those PPMs are too high as well. Your water probably doesn't have enough alkalinity in it to hold the buffer and that soil probably doesn't have much lime in it. You could topdress in some dolomite but it doesn't take effect super quick. I think there is a powdered dolomite called hydrate lime that works faster. For now, just feed lower PPMs, like 500 (which will be less acidic) and then PH up it to 7.5 or so and see if you can pull up the PH, also topdress with a few tablespoons of dolomite ASAP. Good luck!