Calcium deficiency on CHEESE?

about 55 days into flowering. paradise seeds cheese. blue ribbon soil which has everything you can think of in it! I transplanted them into new soil the first day of flowering. up to now i have been watering them with 50/50 tap/RO and a 1/8 teaspoon epson salt per gallon phed to 6.5 because my tap water reads 1000ppm on those test strips consistantly and my town is known to have shit water. ive never run into a calcium deficiency with this recipe. they all are doing it and it started with the largest nugged plant(its obese) which would have the largest demand for calcium i would think. I have not fed them any type of fert in flowering. It starts on the upper to middle/upper leaves. its on the the leaf veins. its really on the leaf veins only which is weird cause i thought cal def causes rust spots in between the veins?????? third pic is under hps sorry!
I have watered them all the same amount since they are all in 2 gallon pots

yes cal def i have the same issue going on got to add some dolomite lime to mine today

Have you looked closely for spider mites?

heres a good guide for def guys http://www.growweedeasy.com/marijuana-symptoms

too much N can cause the dots and burnt tips