I've planted these sweethearts from seeds around 4-5 years ago. I live in a high humidity, fairly mild climate without much sun. I've kept these mostly indoors by window sills and for the past 1.5-2 years they've been by cornering window sills facing west and north (I know they're not the best but that's all the windows I have).
I think I had over watered them for a while, and the soil was full of fungus gnats, so about a month ago I took them all out of soil and sterilized the soil in oven (low heat and about 30 minutes to avoid burning). I also sprayed neem oil + soap + water mixure all over the plants to kill any other existing larvae. I then got an 8 liter pack of citrus soil and mixed it with the existing soil and repotted them. I also took the advice from the guy in the store to keep them outside during summer. It got very windy and stormy a couple of times and I ended up bringing them inside, but a few weeks and one of them has turned very yellow. The roots seem ok but the leaves don't look fine.
What about the yellow leaves on these other ones?
P.S. I use citrus feed every now and then when I'm watering them, but as I mentioned, I'm trying to minimize watering because even though the pots have very good drainage, I think due to high humidity and plastic pots, the soil remains damp for a long while.