Autoflower Bruce Banner DWC

@crimsonecho. 1. My temps are around 28C. And I do not have a chiller. 2. The water is very hard, with 411 ppm out of the tap. I have a hard water Nutrient Trio from Terra Aquatics. Tried Grow - 0.5ml/L, Micro - 0.2ml/L, Bloom - 0.2ml/L, Hydrogen Peroxide 6% - 1ml/L. That raised the ppm to ~600. Kept a couple of days. When I saw this tip burn, I changed the water and just added Hydrogen Peroxide and Micro. The ppm was around 500. 3. My PH is very unstable. Around 8.0 out of the tap. I added 19ml of PH down (phosphoric and citric acid mix) to bring down to 6.0. It got raised to 7 overnight. Added 10ml of PH down again.

i can help you differentiate between the two with one simple question fyi.. are your temps too high, exceeding 29-30C? what are you feeding this gal by the way thats helpful to know. usually when its light stress the leaves will not point upwards in a praying pose. so anyway what are feeding it with?

Looks like light burn, look at the leaf tip, when is burned with nutrients has a different color and is only the pointy tip, looking at your picture, it has the tip and a little bit, this will increase. by the time, also tips look dried but yellowish, not brown color

I disagree with others saying it is from high EC, 320 PPM is really low. She's looks stressed. Probably heat problems, root issues, the nutrient change and the PH swings. Make sure the roots are healthy, your environment is good, and your plant will be fine.

Autos start their nutrition in hydroponics their first week at 200 ppm. If their good the next week is 300, if their good the 3rd week is 400, if their good the 4th week is 500, if their good the 5th week is 600 and you stop increasing there., unless you see that their really wanting more food. Keep your water cool and your ph set at 5.8 until you see actual buds around button size, then bring your ph up to 6.2 for early bud and 6.3 for mid to late flower. Check your ph daily and adjust as necessary

Nutrient burn , the ppm is to high at this stage. Good luck with your grow