hi man you have PK deficiency because the nutrient ratio is incorrect : cut out the grow and keep the bloom and it will stop spreading. You can see the PK deficiency from the edges getting burned in that way. So the proportion of nutrients is also important not just PPM you want something like NPK 1:3:3 so the plant can get the PK. get it ? PPM goes up and down that's normal, even during the course of a day and between day time and night time PPM will shift one way or another. that's not the problem. Hope this helps ! ๐