Leafs are starting to yellow and dry

Hi
As everybody almost in this forum have a problem with my plant, as you can see from pictures below leafs have a yellow dry edges ( these leafs are from bottom ) , I am growing in soil and this problem accord at 3 week. My pH level is 6.7 using GHE Flora nutrients.
I would be glad to hear some opinion about this problem
Thank you guys/girls J

it is definitely not a nitrogen burn as the leaves are light green.
tho it may be nutritient lockout resulting a phosphorus deficiency or mg maybe.
i have exactly same looking leaves on my plants and trying to figure out.plants are all light green cant get them darker.

Looks like K def and/or Mg def. The leaf tips curling and interveinal yellowing points to Mg, and the pattern of necrosis moving from the leaf margin inward points towards K def. There are no signs of nute burn unless it was on the part of the leaf that's already dead.