Rote Blattspitzen

Hi mate, For fertilizer problems all you have to do is a runoff test. Measure the EC in plain water(typically between 50-150 PPM) and water the plant with problems. Collect the runoff water from the tray and measure the EC again. I've seen some growers reading 6000 PPM(EC 12) from the runoff and that means your plants roots are almost burning :) If you read something below 400-500 PPM then you are feeding at the proper dosage. In this case there can be a problem with the fertilizer ratios but for %99 times people overfeed their plants. Focus on the first scenario for now. Let me know what you read when testing the runoff water with an EC meter. Hope these will help.