Yea me too, but I'm not chilling in current system. I took smallest, mostly dead plant down. Other 5 are doing well with just the water level change and fresh nuts. I will monitor closely, but hopefully I won't need the ph down regularly.
So my PH with the pen is 6.3 to 6.5, I have door dash delivering the PH up/down in a hour.
I also noticed that I believe my water levels were way to high. I have them in a rock wool 6" cube, but I had the whole thing summered in water. It wasn't getting any o2 from stone at all, till the roots dropped down far enough out of cube. You can see how high the water is and no bubbles at all. The others are the hardest hit MK plant, roots look good was going to get rid of but I will put back and see if it helps for a day or so.
I have dropped down water levels, will rehanged water on all today and drop my PH down .7, to 5.9 or 5.8, got them in the dark now, will start changing water today when PH stuff is here and I know how much to use.