Getting into the hobby

This week was a bit stressful. I was trying to identify the nutrient excess/deficiency. I think i narrowed it down to calcium deficiency, but these symptoms could also be a side effect of potassium excess (but what I gathered from my research, there is a very slim chance of this). Anyway I started to add CalMag to my regular waterings and they're showing some correction. I'll probablly water them with water, CalMag and lower than recommended amounts of nutrients for a day or two just to make sure. I had them on a 12/12 light cycle for 4-5 days, they've streched and risen up, which was what I wanted. They now on a 16/8 cycle.