Leaf tips turning yellow

My Kosher Kush is having issues, actually all my plants are doing the same thing. New leaf tips are turning yellow and some of the older leaves are getting brown spots.
3 gallon pot, straight fox farms ocean forest soil with no amendments, water when pot is dry and light with tap water aprox every 4 or 5 days. Tent is inside stays at around 85 degrees and 45% humidity Plant sprouted on July 26. Have been having problems with gnats have been treating with mosquito bits and neem oil. Could it be the tap water? Checks out at around 6.5 ph tested with litmus strips.

If you havent been supplementing the nutrients in the FFOF, it's time to start adding. I would start with 1/2 strength on whatever nutrients you use.

Also, water every 4 to 5 days on 3 gal pots at that temp/RH range and with plants that size, sounds like it might get too dry in between waterings. When you water, totally saturate the soil. Then feel the weight. Water again when it is significantly lighter, but don't let it get bone dry.

For the gnats, mosquito bits on the soil are good. Use sticky traps to catch the adults. Neem on the leaves does not do much for the gnat issue. It helps with other stuff, but bugs have to eat it to get the effect, and the adults dont feed on the leaves. Its the larvae that mess with the roots. Mosquito bits will help with the larvae. Youve got to break the life cycle, so they stop reproducing in the soil.

Thank you for the info, I will do these things. I'm doing another grow in the Bruce Bugbee USU soil mix using jacks 20 10 20. Will that be ok for FFOF? Once again thanks for the reply, for a so called weed this stuff sure is temperamental.

I've never used Jack's nutrients, but I know plenty of people use that successfully. I use GH Flora series or GH Maxi series for base with some other supplements. I cant tell you what works for Jack's.