Op needs to do alot more reading! Leaves turning pink means it's a potassium deficiency? wth? You say you've done hundreds of hours of research, yet after all that, you're still not sure if calcium (the element that should be present in highest quantities), is mobile or immobile??? You need alot more reading done..and some of the advice or suggestions here make no sense either...nutrients travel upward or whatever someone said lol..oh my. First off..your humidity at 70% is a disaster!!! In flower, what do you think will happen? With humidity being so very high, plants don't need to take as much water from the medium, they take it from the overly moist air, which contains no food for them! Once you know your ph, and with your mix, it should be low 6's...not past 6.4 for sure! ffof is not soil..not all 'dirt' is soil..its sphagnum peat moss for the most part with some amendments...that alone should be given 5.8-6.3 waterings..add in coco..and ya..above 6.3 is easily too high and would also cause an issue with calcium. That purpling you see is from temps dropping too low, and if it does, even for just one night, you will see those pinkish/purple tints on the leaves! Combined with the high humidity, and yes, you may very well be looking at mold, if not now, then by harvest for sure..inside the buds...botrytis. Get the humidity back to normal..40-50% max..overnight maybe can approach 60% but not higher...and temps should stay very close to 70..ideally not under 65 at lights off. You say your watering was very low ph last..4 or something? That in itself would make aluminum more available to the plant, which also would cause issues with other cations, namely calcium, magnesium and potassium.