Yellowing leaves and burn spots during flowering, appears to be getting gradually worse.

Got all the way to flowering. And I'm noticing drooping, burnt tips, yellowing on one white widow and dark green and slight leaf curling on one wedding cake. My initial thought is nute toxcity and possibly over watering? I water about once a week. I pH the run-off after each watering and getting around 6. Both plants were thrown into flowering...maybe 4-5 weeks ago. I've switched them over to bloom formula per the fox farms guide.

Grow Info:
Indoor microgrow.
Coir and perilite grow medium
LED bulbs
Foxfarms liquid fertilizer
Water with Reverse Osmosis water, cal-mag added.
Temps are kept at about 80 F and 35-40% humidity.

I don't understand how it could be nute burn as I cut the recommended amounts down to half and water with pure RO between every feeding. Can I get a more experienced growers opinion? Any other critiques are welcome. It's my very first grow and I'm sure I missed something.

The pure ro water can bring your ph down over time. Depending on what ph went in when you had 6 ph runoff, it’s either low ph or nute burn in my opinion. Also, ro water is hard to ph accurately without ions.

Redskare87 said:

The pure ro water can bring your ph down over time. Depending on what ph went in when you had 6 ph runoff, it’s either low ph or nute burn in my opinion. Also, ro water is hard to ph accurately without ions.

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The clawing leaves are a really good indication of nute burn

Redskare87 said:

The clawing leaves are a really good indication of nute burn

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Thanks for the reply. I always pH the pure RO to around 6.3 when doing watering in-between feedings. I'll do another plain watering or water down my nutes further.

i've always had problems using RO water for some reason.......apparently you should buffer with 20-30% dechlorinated tap water.

if ya in coco try watering more often

Redskare87 said:

The pure ro water can bring your ph down over time. Depending on what ph went in when you had 6 ph runoff, it’s either low ph or nute burn in my opinion. Also, ro water is hard to ph accurately without ions.

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Am I correct in saying the burn can still come from a normal feeding if there was no watering in between to push out the last feedings leftovers?

HydroKid239 said:

Am I correct in saying the burn can still come from a normal feeding if there was no watering in between to push out the last feedings leftovers?

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Yes you are, a normal feeding can definitely cause burn if the plants aren’t up taking all the nutrients and more is added. You can determine how much the plants uptake via ppm/ec/ph in and ppm/ec/ph out readings. I couldn’t explain exactly how to use the scientific approach, but it’s definitely worth looking into. Cheers