1/10 - Day 56 / Day 28 Flower The nutrient deficiency appears to be getting worse. After some reading, I suspect I may have a pH issue which is causing a nutrient lockout. I gave each of my plants enough water to get some runoff that I could test. When I first tested the runoff, I was getting pH readings of around 5.6-5.8 for my 5 gallons....not good. Way too acidic. I decide to do a flush out of an abundance of caution. I ran about 8 gallons of water that ranged between a pH of 6.5 and 7.2. At a certain point, I ran out of distilled and dechlorinated tap and decided to stop flushing at that point rather than introduce chlorinated tap water. At the end of the flush, I was getting pH readings of around 6.1 and 6.2 for my 5 gallons. Not ideal but should at least mitigate any further damage. Remarkably, some of the leaves that were starting to yellow began to bounce back shortly after the flush. **************************************************** 1/11 - Day 57 / Day 29 Flower The conditions haven't dramatically improved but also haven't appear to get dramatically worse. The leaves that were already yellowing seemed to yellow a bit further but I didn't notice any new leaves yellowing. After still more reading, I think I narrowed the issue down to a magnesium issue. My leaf symptoms seem to match all of the tell tale signs - leaves were turning pale green before fading to yellow, the yellowing was showing up first around the edges but all the veins were still green. Combined with the fact that magnesium lockouts typically occur when the soil is too acidic - I think I found my culprit. Even though the soil was still wet on my 5 gallons, I decided to go ahead and provide a half gallon of distilled water with 5mg of Cal-Mag to each plant. Of course, this was before I read some of the responses to my grow question and this was the exact opposite advice suggested by @BluntZilla who I think has the correct diagnosis of my problem (calcium toxicity causing other nutrient lockouts)... :facepalm: **************************************************** 1/12 - Day 58 / Day 30 Flower Based on the symptoms I'm having, it looks like the biggest nutrient deficiency I'm having is magnesium. In an attempt to mitigate that deficiency, I made a solution combining a gallon of distilled water with two tablespoons of epsom salts and applied as a foliar spray. Started applying this today - once in the morning and once in the evening. **************************************************** 1/14 - Day 60 / Day 32 Flower Watered my plants using spring water until I could produce runoff. The runoff readings were as follows: Z51: - pH = 6.4 - TDS = 1080ppm - EC: 2.2 Z52: - pH = 6.3 - TDS = 1040ppm - EC: 2.1 While it appears my pH is back in a healthy range, my EC readings are a bit higher than I'd like. Ideally, I'm aiming for 1.8 but didn't want to continue shocking my plants with a flush. **************************************************** 1/16 - Day 62 / Day 34 Flower My plants still haven't really turned a corner with the nutrient lockout issues as new leaves continue to succumb to the same symptoms of slow yellowing. Despite these issues, my buds are continuing to develop and becoming more full and dense.