Leave's tips are drying. Please advice.

Hi
Attached are two sets of photos of the leave's problems I am experiencing in my new grow batch. These are grapefruit plants in Fox Farm Ocean Forest (FFOF) soil. 10 days ago I noticed the top soil of most plants had yellow/orange perlite, the soil looked yellowish and the pots drainage holes (see pic 2) had a fungus looking yellow/orange specs.
I sprayed the soil and leaves with Neem oil and the soil alone with NoDamp fungicide. Now the soil, and perlite and the holes are clear.

Problem is leaves (usually lower ones) lose green become yellowish, and the tips and tip’s edges become brown or grey and dies (see photos). The soil is 2 yrs old but not used before only mixed with a bit of perlite and vermiculite.

Is this still fungus? Is fungus deep in the soil too?
Or
Could this be nute burn although I added nothing (no nutes) to the soil yet? I did a mild foliar feed with SuperNatural GreenStay (Nitrogen) and the green in the leaves intensified so I started to suspect nute lock due to lots of organic nutrients in pure FFOF soil. Should I have mixed the FF Ocean Forest down with regular soil or peat moss to dilute its organic nutes for the seedlings?

Or any other suggestions?
Whats wrong with my seedlings. PZ advice.

Tell me ,what point are you at with these plants? Days, flowering or veg, etc. mine began having yellowing of lower leaves as soon as I put it into flowering, I just let them be, if your just starting out (2 - 3) weeks thats how old they look then maybe it's a nute deficiency but I doubt it.

3 weeks from germination.

Well, I dunno it's hard to say I can only speak from experience, haven't had that happen until flowering began, but it looked just like your photo. The tips got brown adn the whole leaf began to shrivel up and droop. Have you checked the plant problem faqs?

I am posting a few more pics with the hope that some one can help me with this situation. Is this Nute burn, Desiese, fungus ...???

GUYS ARE YOU GONNA STAND BY AND WATCH MY CROPS DIE? pLZ SAY SAOMETHING. YOU REPRESENT THE DOCTOR AND THE PATIENT IS DIEING.

i think like you said it's most likely nute lockout, or nute overdose but if you haven't given it any then probably not that...you check your pH? or it might be a reaction from the nutes in the soil. i had this but not till flower and i think it was a buildup of salts and such from nutrients and not flushing. just flushed yesterday i'll see how that works. it was like that for a little bit and then many more of my leaves started dying, so i would possibly recommend a flush.

but i do recall seeing a sort of burn like you have on the tips and leaf edges in the FAQ for Mg deficiency or something like that. check out the one with the pictures, you might just be short on a certain something

damn i was hoping for a solution in this thread as i have the EXACT same problem! maybe even worse..the thing is im using DWC not soil and my plant like yers is 3 weeks old and looks about the same height. as for the nute burn theory, i dont think its nute burn, i flushed my plant for a day and a half with just ph'd water, mised a VERY light solution of nutes (im talkin like 0.4 EC) and leaves are still having this problem! also has yer growth sort of stunted? mine has a little...i dunno about fungus, its a possiblity, i've got little white spots on the surface of my rockwool...

Problem is better but not gone. I have become more tolerant since last grow cycle. Less of a perfectionist. As long as the new growth is constantly happening and nute lock or whatever this is is on the old leaves, who cares.

Will report later.