Hi Everyone, I know this topic has been discussed many times, but I want to be sure I correct the issue so that I don‘t make the same mistake with my grafted trees. Over the past two weeks, one of my lemon seedlings developed light colored areas on the top leaf. I have sprayed twice with horticultural oil and twice with FP since bringing them in in October. I pulled it back from receiving direct light (LED 65watt - 15 hours a day, 7 days), thinking it may be bleaching. This week, one of my Valencia seedlings started doing the same.

Note: I have been feeding FP (1 tsp per gallon) every other watering since they have continued to grow; mist with water everyday - they dry and do not hold water on the leaves. Could this be salt build up? The Valencia is in a 5-1-1 mix, the lemon was in a poor mix, but repotted into 5-1-1 a few weeks ago. The light areas showed up right before repotting.

Thank you for your time and assistance!