I was having some leaves curling under yellow tips.. I thought it was nitrogen burn but idk I'm not sure if it was mold fly larve or something. It was outdoors.
Gonna bump up the timer to 18...
Im using a 100w terrarium plant bulb, as i felt the tao tronics 36w led was not doing much but hurting my eyes(is that normal?)
keeping Temps in the 70s (60s at night)
Fungus gnats wont usually hurt a plant too much. They are more of a nuisance. If there is a huge infestation it can kill a plant but there would have to b hundreds of them and they are fairly easy to control. I use a combination of fly paper, homemade bug spray, and if its really bad, water the soil with a hydrogen peroxide solution.
Leaves curling under can be pests or too much nitrogen like u said. The yellow leaf tips are usually from over watering which might also cause the curl. Some pics would definitely help with diagnosis.
Your temps sound good.
As for lighting, i have never used led but am looking to in the future after i do some more research. Metal Halides are really bad for the eyes so stay away from those. A good rule of thumb is to have at least 2000 lumins per sq ft. 3000 at most.