Red Poison: Sweet Seeds

I go into the local Hydro store and the previous owner happens to be there. We talk about my novice grow and I mention the "Calcium" issue as I show him a photo.... He immediately asks me " Are those pots on a concrete floor? Because if they are, your roots are getting cold making it look like a calcium issue".... The new owner gives me a nice slab of styrofoam from an old box to put on the floor of my tent as I go home. I sick my BlueLabs PH soil pen in a drain hole at the bottom side of my pot and HOLY CRAP its only 17c and the PH is 5.2 !!!!! I take the plants to the bathtub and flush them with clean water PH'd to 5.8, about 8L of rinse per pot. I check initial run-off and its a whopping 2300ppm/50!!!!! I also remove some of the effected fan leafs in hopes I dont get some sort of plant illness. A day later I do the same PH test, PH is 5.8 and temp is 22C...all is well again. I should have paid attention to growing saying...make sure you get run off checks.