Leaf tip discoloration: light or something else?

[Mugwort]

Still hoping to find definitive answer to discoloration of leaf tips and pistils. I am hanging two ViparSpectra XS-2000 lights. Initially they were hung (for a short while) at 18”. PPFD map in manual states at 18” and 100% PPFD is 830 at center for one light. I raised to 24” after noticing pistils on one strain turning reddish-brown 18 days after switching to 12-12. They are nearing the end of 4 wks.
I grow in FFOF. I am careful to not overfeed.
—2ml Atami Bloombastic/gal r/o water every other day. Started this beginning of 4th week
—5ml CalMag plus/gal r/o water 1-2 times/week
—5ml Snow Storm Ultra 1-2 times/week
—water every day; water without nutes every other day
No vegetation N based nutes since first week of flower.
—Alternated “Flower Fuel” and “Kool Bloom” weeks 1-3. Administered every other day
My feeling is that I placed the two lights too close initially but am not sure. Certainly there must be a way to, at least roughly, using a PPFD map for one light to figure the closest distance one can hang identical led lights considering overlapping fields of two separate lights. Come on you photon geeks!

 

[Anthem]

over feeding causes tip burn.

 

[Mugwort]

over feeding causes tip burn.

A truer statement cannot be made!

 

[SmokinJo421]

Over watering....some stress is beneficial stress. Really need to mimick outdoor stress, dry cycles, wind, movement, temperature changes, etc!!

 

[Its420anytime]

Normally leaf tips burns are attributed to nute burn.
I have 5 gal pot 4 pots, they only require water their whole duration. Shouldn't ever have nute burn, yet I have on all my plants.
Great for autos.
Never had over watering issues since 70s, then again 6 in pots and sog with automated water systems and now leds and hand watering. I use the feel method for determining watering, will pay attention to more closely. I never remember leaf burns from mh and hps lights from water droplets on the leaves, but leds magnify those droplets and will leave a spot.