Your right I tested with two of my pens are on point and my brothers pen same readings I'm just feeding what it needs been playing it by eye and it's been hell of work doing so because at points in time I would have to slightly lower or go higher a real pain but almost done and what a difference as I ran her last in promix this shit is on steroids in smell and crystals and denser
I had a guy say yesterday yo have you try gg#5 I said no he claims it's fire so joesy how much better is it was told #4 still holds the crown
pens have must have come along way then. when i had oakton pens those would never be right, it would shut off an i would turn it back on an read the same nute mix an it would read a different ph then 10 seconds ago. i swore those pens off 5 years ago. glad they are working for you thou.
try the royal gold coco next. other buddies i know been using gold label for awhile too. seems to be on point so far.
bsafe