Hi All, I was hoping someone could help me identify a potential problem I am having with my hydroponic Kale. They were going fine and then one of the mature leaves turned yellow (and then interestingly it went green again). I then started seeing new yellow growth. One of the mature plants also appears to have some dead spots. I've also noticed some leaf curl on a mature leaf and in some cases total leaf death. All of the problems are pictured below. The problem seems to be accelerating. I've noticed some algae growing on the vermiculite that is at the base of the plants, could this be a causing such severe problems? Nutrient solution is around 2-3 weeks old (was planning to change this weekend, what is the recommended change frequency?) The tank is also growing lettuce, basil and coriander all with no problems. Specs: DWC (30 litres / 8 gal) - Water is aerated, 2.5 litres per plant (above 2 litre minimum for small plants). Water Temperature: ~15c / 60f overnight to 20c / 68f daytime Ambient Temperature: ~12c / 53f overnight, 20c / 68f daytime. 18hrs of T5 light per day (distance of mature kale leaves from globes approx 70mm on average). nutrients (16ml diluted into 30l / 8gal) - resulting cF 8 NPK (24-6-31) Calcium 21.4 Nitrogen 24.25 Potassium 31 Phosphorous 6.2 Sulphur 8.60 Boron .009 Copper .005 Molybdenum .0003 Iron .2 Manganese .009 Zinc .02 Magnesium Sulfate (1.5 teaspoons per 8 gal diluted and added manually). pH maintained between 6 and 6.4 Any help appreciated.
