Background: Plant was abused when little. It was stunted at 2" tall for 3 weeks. Then it grew roots and started growing again. Now turned a little yellow on new growth. Note on top in picture is much worse than it looks compared to lower green fan leaf. Also not slight mottling on the lower fan leaf. http://www.enduringcactus.com/yellowe.jpg Blueberry, six weeks old, 11 inches tall Bubble Bucket Hydro Ph 5.5 to 7.0 (meter has been out of whack sometimes) Nutrient Level (estimated, waiting for meter) 500 HPS 400 Watts 18 inches from top (burned plant last week, raised lights) Lights on 18 hours per day So a few days ago the yellowing started. I figured a zinc deficiency and raised nutrient level. Also applied nutrient to leaves via spray. No change in yellowing in past two days which made me believe I have a lockout. So today I flushed plant, roots, and changed water. No nutirent added yet as I need to get calibration fluid for PH meter. Any ideas. It's my first hydro grow and I have done just about everything wrong. All comments will be greatly appreciated. Can't wait for nutirent meter!
Looks like it could be zinc, iron, root trouble or temperature swings. All those will yellow from the top.