Athosanswered grow question 7 years ago Yo darkmanx. There are two things you can improve.
First try to lower your res temperature between 15°C and 20°C (59°F to 69°F).
Lower your solution strength to 1.4EC (700PPM), what you are seeing is potassium (K) toxicity, which locks out many other elements. Since you are using a LED bulb, there's no point in using a too strong nute solution.