Do you know the TDS reading of the tap going in?
The plant is well established enough that you should be following wet / dry cycles and watering to about 20% runoff on a regular basis now. I forget, 5 gallon pot? She’ll probably take somewhere between 1/2 and a gallon per watering and look for about a solo cup or so’s worth of runoff. Without that you’ll start building up salts in the soil.
Don’t worry about runoff again at the moment, do the soil slurry with distilled, get the readings and we can figure out where to go from there. The slurry test is going to give you very accurate readings of the soil itself which will be helpful at this point. If you’re not sure how, lots of resources on YouTube or in here. Very simple, painless, and accurate.
Also, when you get a minute, post up some numbers from your tap water out of the PUR filter. (don’t bother PHing, just post the straight readings so we can see what you’re working with.)