Ok. I've had a problem with leaves yellowing. It started on one plant, one leaf turned yellow, then a couple more, and a few more, and on another plant, progressing the same way. First one leaf then a couple and the next thing it's taking over. I noticed it starting on 2 more tonight. We are now 20days into 12/12 lights. The plants are of the ever-popular Bagseed variety, and this is my first real grow. Can't really say what kind of soil I'm using, started with a locally mixed organic then got some cheap orgainc soil at Lowes. They have enough light. I'm using Technaflora Recipe for Success nutes every third watering. I check solution and run-off ph, but my soil meter doesn't work. The run-off comes out slightly higher Ph. This has resembled a few different deficiencies, N, K, S are the 3 closest as far as how the leaves look. I have given plain fertilizer for Nitrogen, bloom ferts and bat guano for Potassium, and Mag-Sulphate/ Garden lime for sulfur, mag, calcium and to buffer ph. All to no effect. Note that the yellowing occurs mainly around the outside and under the canopy. I'm at a loss as to what to try next. Does anyone remember having a problem like this?