Nut lock

looks like bronzing from chloring toxicity.. but if it was just a lower leaf being shed and isolated, nothing to be worried about.. it'd be tough for this to happen - a Cl tox. the chlorine in tap water is not high enough to cause this in 99% of places. The old wive's tale to leave your water out for 24-48 hours does more harm than good, unless you aerate and agitate during that time, otherwise the stagnant water will have a far larger negative impact than some minute concentration of Cl. so, added anythign with cl? a foliar spray? eliminate possibilities... and liek i said, if the plant shed a couple leaves and the rest looks fine, it's nothing.

Worry only about the pH, not the colour of the water. This is a deficiency of P/K, not pH and it is something cal/mag won't fix either. Remember too, what is showing now in the leaves is related to what happened in the soil 2 weeks ago. These symptoms first appeared in your diary in week 7, the first week of flowering and is exactly when the need for P and K go way up in flowering cannabis. You say this is your third grow and this same problem occurs each time, yet you don't change anything and when Growing Grannie offers you advice regarding a P/K issue, you dispute her help........as she said.......double you P/K additive and your problems should reduce greatly. Obviously the damaged leaves will not recover, but it will help it from becoming much worse. In future you will have to start with your P/K additive much earlier than you have been to prevent this problem in further grows.

Yes give your ladies a good flush until your water comes out clear becouse Brown is feeding

I wouldn't worry so much about the color of the water - even your soil can affect that... what you want to do is to make sure you've run enough water through her... that's the pot volume x 3... at that point, the runoff you get should be the same pH as what you've been giving her... if not, keep giving her more water until it is. She'll be good an "rinsed" then and you can let her dry out. When she's dry, her first feed should only be 1/2 strength ... keep the nitrogen-heavy nutes at 1/2 strength going forward but you should also be adding some PK booster since that's what she's desperate for.... Good luck!