Help!!!!!!! My leaves are drying and have rust looking spots

hello to all. My plant is in its third week of flower and in getting some dry leaves with rust looking spots, one was very very dry... Please help. They did have one day of extreame heat...100... Please help the pics are front and back of leaves.....

pH? Calcium possibly.. Salt build up is another.

coho said:

ph? Calcium possibly.. Salt build up is another.

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my run off has been low it was 4.2 5.5 /6 going in. I add nutes after ph test.. That could be throwing it off ....I HAVENT REALLY FLUSHED IT SINCE THE FLIP.... SHOULD I ? AND HOW OFTEN?

Hey...

Looks like the same exact problem I just had. I'm going to say you do have a nutrient deficiency but you also have PH lockout. First things first, PH your water, whats it looking like? Then PH your soil... whats it looking like? Finally, go ahead and mix some nutrients and then PH them!

beyond PH you probably need some Cal/Mag