help with ladies-suspected nute burn help help

my plants are about 3 weeks old and were doing well now the leaves are turning yellow and brittle and another is starting to turn yellow ph is at 6.5 with nutes running 400 watt hps through whole life 18 on 6 off at the min
i have 2 the church and 1 sharksbreath

its looks to me like it could be nute burn or bugs.
how often do u feed them fertilizer and what is the N-P-K (example:10-10-10 or 5-5-5??)

Some people use diluted nutes for young plants. Indoors, or outside? If you're growing outdoors the chance for bugs increases considerably. They look nute burned to me, but I am but one opinion. Best of luck, cheers.

Looks like light burn/heat stress to me. Nute burn would only happen at the tips of the leaves first and its not pH problems.