Very Sick Girls-Need Doctor-Pics

I've been fighting this yellow tip thing that is moving to the margins of lower leaves then taking over the entire leaf, some stems are purple and one main stem has purple strips in it

First thought it was Potas def so i started feeding with MG Tomato Food 18-18-21 still same

Then thought it was Nitro def so i flushed and feed only 1/4 recomendied amount- still same -VERY Frustrated -rapidily moving up plants

Use tap water, leave out for 2-3 days then ph down to 6.5 with vinegar

Water Ph-6.5

Run Off water-6.5

Room temp-78-80

Water every 4 days or when soil is dry

Good air flow and Vent

Humidity 35%

you have been feeding them too much my friend you missed out how old they are and what stage they are in but the fert you are giving them are too high in npk for mary jane !!!!!! pics would def help diagnosis