Yellowing fan leaf tips advice

[gmul92]

Hello I’m experiencing some yellow tips on several fan leaves. Looking for some advice and feedback. I believe this was caused from water with high PH. Two Autoflowers are about 1 month old. One female is about 2 months old.

The details:
2’3” x 2’3” x 5’3” grow tent
(1) marshydro 300w LED
(1) HGL 100 quantum board
-hung about 18-22 inches away from top of canopy

Temps always range from 72-82 F
Humidity ranges 40%-60%

3 gal fabric pots
Bottoms filled with kindsoil, top filled with coco loco medium

(1) female cosmic railway
(1) gorilla glue autoflower
(1) tangerine dream autoflower

Been watering about once every 4-5 days. Rushed last water and didn’t check PH. Left tent unchecked for 2 days and when I checked noticed yellow fan leaf tips that have progress a bit more each day since.

I have been using Poland Springs and Smart Water for my water source because kindsoik required water as close to 6.5 as possible. I have ordered some natural citric crystals to help lower ph of water for future.

Does this look like damage from high PH’d water used?? Or some kind of other defficiency ?

Also interesting that the older, female didn’t experience any yellowing from the same water used on the autoflowers.

Let me know your thoughts !

 

[AngryBird]

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• AngryBird
• Aug 17, 2016

nute problems 2

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Is it spreading or just on these leaves?

 

[gmul92]

It looks like late stage zinc deficiency.. and it’s happening only to fan leafs closest to the ground off my main stem

 

[Far East Buds]

Most of the issues I ever had was PH related. The absorption table will show that ph to far out of range will not let certain additives through to the plant. So even if you add zinc if the PH is way out of range it may not absorb it. A serious flush and refeed with correct PH and balanced food/water. Don't chase the PH. Just as close to 6.5 (soil?) and you should be good.

Good Luck

FE

 

[3fingerdSean]

When leave tips scorch on old growth its a potassium deficiency.

 

[MassMedMan]

I wouldn't worry so much about that old growth since they're autos. And since the other didn't show it,,,, I'd rule out the water. But, two beans from the same strain do behave differently... anyway. The dark veins look like a cal mag or slight nitrogen deficiency. More the former since you're under leds.

Are the stems of the leaves purple?