Yellow edges and brown spots on marijuana leaves

A question from a fellow grower:

There is some yellowing on the edges on older leaves.
They are about a month old.
these are grown under a 4-tube standard kitchen fixture. I swapped one bulb for a “grow” bulb.
plants are 3-4 inches under tube.
the fixture came with a clear decorative defuser, still installed
no fertilizer has been applied yet.
soil is store bought for seedlings
what do you think of these?
should I pull-up the super silver (middle pic) as it seems deformed and took a long time to come-up.

swim had a similar problem and failed on the 1st grow because of it. Never did find out exactly what the problem was but narrowed it down to PH problem with the water, no air extraction at all in 1st grow and RH problems. For swim it was most probably PH problems because he used to ph adjust the water in the 1st grow and the yellowing was there but stopped doing that and even stopped checking the PH completely in grow 2 and they are super healthy.

There is nothing wrong with your plants. Put them in a 1 gallon pot with a good potting soil. You could kill the little scrawny one, but never give up on a plant. until it gives itself up.