If this should be in the sick plant forum im sorry, I thought this would be more apt since this seems to be an LED related issue. Short story, since i switched to cobs my PH rises crazy fast and Im seeing classic magnesium issues Long story: I recently build some LED lights out of Luminus cxm-22 cobs. Im running 2x lights in a 4x8 tent. Each light is 10 cobs mounted in a xxxl hood running at about 72w each. So Im looking at 1440w per 4x8. They are 3000k and a 50/50 mix of 80 and 90 cri. My plants are in titan flow and grow system, Ive run this system before, and i have another 4x8 right next to this one that is still 1khps and all is fine. I had another 4x4 with one of these lights in it, i had the same issue. One of my drivers died so I have 2x 315 CMH in there now and the mag and ph issue is gone. (the 4x4 is a flood and drain table) I use jacks hydro and calnit with some added microbes and geolite/rocks as my medium. my room temp is 80-84 with lights on, my leaf surface temp is 76-79. Ever since I moved to cobs, this tents rez PH is rising rapidly. IE I PH it down to 5.6 with botanicare phosphuric acid ph down and by the evening im at 6.5+ I am also seeing classic magnesium def signs. Ive washed out my rez, I dont see signs of algea or anything crazy going on in the root zone, although my plants have filled up the buckets with roots, could it be root bound? I just recently saw on PLC site that mag should be in the 75-90ppm range, my jacks is sitting at like 25-30ppm so i JUST started running my nutes as such: jacks 3g cal-nit 2.5g mag sulfate 2g diammonium phosphate .25g (i read the ammonium base helps buffer PH lower, doesnt seem to be working tho) growsil .25g This has my mag at 75ppm exactly I'm pretty sure. so, any ideas whats going on here? Like I said I have several other tents going with HPS, CMH, and even a veg area with citizen 6500k cobs and none of them are giving me these issues. Its JUST the cob tents.