Hey guys, I recently inherited my buddy's op due to extraordinary circumstances, 4 sweet diesel females 15 days into flowering, after a 2 month veg from seed (they've all been supercropped or fimmed can't remember). I'm running them in the same setup they were previously in: 250w HPS, three 24w CFLs for side lighting all in a DR60 tent. For the life of me I can't remember the specs on the duct fan, other then it's 6mm and loud. It's a soil op(FFOF, hydroton, worm castings and coco coir i think but i'm not 100% sure) so they each get fed 2 cups of distilled water and nutrients every other day. The regiment he has me on is a combination of cal/mag, bat guano(indonesian), sweet (synth carb), superthrive, and bloombastic. There's also some Grow Big and another type of bat guano for nitrogen supplementing. I've noticed an alarming amount of purple developing in the stems and stalks of all 4 plants. There's been a recent cold snap in my area and the room has been in the 50s at night for a few nights in a row... I'm not sure if it's the cold that cause the yellowing and purple stems or if it's some kind of nute burn/lock? Some feedback would be much appreciated.