Salt buildup in the soil.
They need to be flushed out and fed with a complete veg fert.
Also they are practically BEGGING for more light... can you hear them? "closer! closer! pleeeease?" Tube flouros= best at less than 3" from the plant tops. After that, not great!
To each quart pot, pour 3 quarts of water through. Then make up a fert solution at ~1/4-1/2 strength (no need to be precise, it's just a weed, lol) and water with that.
Make sure you have very good ventilation too. You want your girls to use up most of the soil moisture between waterings. Soggy soil can and will contribute to symptoms like you are seeing in the presence of too much fertilizer.