Bubba Island Kush - DWC

i come to the conclusion that i had/have a quite severe N toxiticy... i refered to the RQS website that says "seedling : 400 - 500 ppm , 1.0 - 1.2 EC" -> i adjusted EC to 1.1 and didn't check PPM.. N tox symptoms arrised... https://www.royalqueenseeds.com/blog-cannabis-water-quality-part-2-ppm-ec-n298 a few days later i switched to PPM which read 740 ppm...shocking...why was EC 1.1 = 740?? i read the description the bluelab guardian and i says PPM = ECx700, so EC 1.0 = 700 ppm... why does the RQS website say EC 1.0 - 1.2 = 400-500ppm ??? does anyone know? strange thing...anyways: now i removed alot of water and refilled with pure RO water and added a few mL of root complex and powerzyme damn PPM mistake cost me a whole week of veg...growth was very slow...usually i wanted to go for flower by end of next week but now i probably need to add another 2 weeks veg i added the 3rd light at the end of the week, so now with nutrient problem solved i hope for explosive growth next week...