What is wrong with this plant? I think I know do you agree?

Im nearing the end of my first grow. Everything has been smooth sailing up until the past couple of weeks. It looked like the fan leaves were dying off at first and I read this is part of the process so I didn't think anything of it. Until, the leaves on the main cola started to dry up and become very brittle. This also effected some of the resin at the top. Then it started to affect some of the older growth on the plant. I spent a lot of time trying to figure out why the PH was getting all out of whack until it just dawned on me. I feel like an idiot. The entire time I've been using the same pitcher to feed the plant, I would fill it up with tap water and let it sit out over night. I did not wash it and I think that putting the water in this pitcher that was stained with fertilizers from previous feeds over night was throwing my ph off. As I continued using it my plant became more and more ill until finally I noticed it. Do you agree? If so now that I've fixed the problem do you think this delayed the process by a week or will it still finish on schedule? I plan on getting a microscope just to make sure.
 
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