Help please!!!

Not sure what is going on. Plants are about 21 days old growing in happy frog soil but for reason my leaves keep turning a rusty brownish gold color around the edges. The temps stay between 68 & 74 degrees constantly and humidity at 39 %. Just fed them for the first time tuesday but this problem occurred 1 1/2 weeks ago!!!

how close are your lights? what lights are you using?

1000 watt mh

It looks like a combination of Phosphorus & Potassium deficiencies. K def usually causes yellowing at the leaf blade edges, while P def causes patches of brown, crispy necrosis. Together, they can cause brown, crispiness on leaf blade edges.

thank you for the info it was greatly appreciated!!!