Is this nutrient burn? Please help the beginner

Hello folks

I am growing three cannabis strains. Mainly I have ,White widow", also some of ,Blue berry" and some of unknown because I had those unknown seeds from more than i year before and can not remember. I am growing in soil with minerals and leca drainage in the bottom. Now it is third week of vegetative stage. I use 800w LED bulbs and before my lamps was too high around 1m distance from the plant so I guess it can not be a light burn. Now I moved it to around 70cm distance from the plant. I use these nutrients

More than week before I had faced thrips and I had used ,Siltac sf" mixed with water spray to kill it. Now I can not see the thrips anymore.

Now I am very confused about the problem because I am not sure if it because of:

  1. Faced thrips and it damage

  2. To much spray of ,Silitac sf". Because I sprayed a lot on the top and bottom of the plant leaves and one time two days in the row starting the day of the plant. I had read after that too much spray can burn the plant.

  3. Nutrient burn. I use 220l barrel and all the time heating it up between 20-21 in Celsius. Also pH in between 5-6. At the beginning I was on the rush so it might be that first time I put too much of nutrients. I also started to notice the edges of the leaves before I had faced thrips but I thought that its not a problem.

Mostly I have problem with unknown strain.

White Widow

Blue berry


Thanks for your time !