My plant is starting to look sick in flowering

Light: 400 watt hps
temp: 80 lights on/ 65 lights off
30% humidty
soil: FF ocean forest
Runoff ph: 6.4
Nutes: FF Big Bloom and Superhume

I nuted full strength a week ago with phed distilled water. Plant was looking perfect 2 weeks ago, now the leaves are starting to turn brown and yellow, the very tips are burnt, and there's slight drooping. The drooping is probably from underwatering since it had been a week since I watered. I watered today with 6.4ph distilled water. From looking at the pictures, what could be wrong?

Are the leaves spotted? Based on the description it would seem over-ferts but the pictures look more like over-watering. Maybe salt build-up in the soil? I don't do soil so hold off for better opinions.

From looking at the pics i think she looks a bit thirsty. Maybe some N deficiency... I don't see a major problem other then that. Keep a close eye on her and let us know if it gets worse. How long has she been flowering for?

It's not spotting but near the middle vein they're turning brownish black. The lack of green isn't N deficiency?

Flowering for a month... I gave it 1400ml of water before I got any runoff today.

MajoR_TokE said:

From looking at the pics i think she looks a bit thirsty. Maybe some N deficiency... I don't see a major problem other then that. Keep a close eye on her and let us know if it gets worse. How long has she been flowering for?

Click to expand...

Why a 2nd opinion is always key - in hydro you don't under-water much...

Looks like maybe a nitrogen def but that is probably secondary. Id say root bound could be an issue which in turn is causing a salt build up which in turn mabe starving the plant as intake is cut.Maybe you can inspect the root ball and see if it is still airy or if its a tightly wound ball that the roots keep wrapping around themselves. Then Id cut back the nutes and water straight water once or twice then hit it with a high nitrogen feed and see if it greens back up but Id check the roots first.Just my thought on it. Hope you find the solution

Would it be ok to nute next watering even though there's slightly burnt tips? If the problem doesn't get better after the next watering I'll pull it out and see if it's rootbound. The plant's not that big though and I thought 3.5 gallons would be fine.