Do you not see this problem in cooler wheather ?
If not it's heat. Your nutes EC kind of high. Even the good leaf looks a little crispy on the edges. I sprayed a foliar feed on some and that's kind of what it looked like plus the water burned yellow spots.
LOC NAR on probation Reviewed by LOC NAR on probation on . bright yellow spots OK - first off, apologies, as my digital cam isn't working...but I can describe the problem pretty well. Set up - one female flowering for about ten days in an NFT system under 250 HPS, with an EC Meter reading of 1.4 consistently in both veg and flower. Water and grow-tent temps exactly where I want them. I change the water every 3-4 days. Plant generally looking in excellent health until about three days ago, when I noted bright yellow spots in the middle of just some of the leaves...not Rating: 5