northern lights auto 1° grow

Algae is a sign of over watering. The algae wont harm your plants. As your plant grows it will shade out the soil and it will die and feed your plants.

Hey there Starter , looks like overwatering , this you can see from the puffy space between the veins of the leafs . Try to let the soil dry up one extra day than normal, this will completely fix the problem and the plant will recover fully. Hope this helps ! 🚀

Cut them off. No reason to keep them unless you want to invite some critters to munch on them.

Nute toxicity. Happened in my last grow. For weeks I taught it was lack or too much water Flushed the plants with a lot of water after a couple of days leaves turned back to normal.

With 40% RH and 30 degrees C it makes about 2.55 VPD (Vapour Pressure Deficit) that is high stress for plant. High temps with high PPM make the plant to consume more nutrients because it's using much more water for evaporation. Lowering PPM of solution will help. As I mentioned in my comment earlier, the plant likely has nutrient burn due to very high ppm is applied once per week. It's better to lower feeding for some time and then feed every other watering (feeding-watering-feeding-watering). Also apply relevant PPM according to temperature. High temperatures require less PPM. That's my IMHO.