... you mean HPK? yeah, that's fine stuff, I've used that before during the Biotabs run,... that Big Up is atomic powered with those numbers, so use it sparingly... all too easy to over-do it with that stuff!
...one thing to note, K defc. and K tox' can show similar symptoms-
.... how much of the BU were you using, and how often? SBG is all P, isn't it? K numbers should be pretty high now regardless,... so for milder boosting the SBG and HPK will work, but it's still light on K,... not sure how "organic" you want to go, but fully organic K is a hard find, so that's why I use the synthetic boosters at high dilution in conjunction with organics,... Another product I've started using is, get this--salt substitute, KCl,... yup, Cl is a micronute (not chloride, not the same thing at all and not available to the plant for uptake),... just a pinch here and there,.. Dudeski, do you have a TDS meter? very handy for making solutions when dealing with synthetics,... I'm surprised how little it takes to get reading over 500ppm,...like 1/8tsp in a L! .... So, this is all balanced with how often you feed,... I try to get things on a weaker/frequent input level, better for smaller pots at least,...keeps the build-up down, and let you read the plant more easily and make changes... that's the upside to using synthetics, rapid uptake!
Other PK boosters, there's a million of them! it's all about the numbers, and what else is in a given product, if anything,... I saw Mr. Ganjamoto made some nice recommendations, Explode and something else,.. gotta go look in the Dutch Pro thread he's in,...
I love the EJ Microblast, mostly sulfate based, so extra S gets in too, which is vital for good terps production along with K,.... micro's play so many key roles, lack of them even at sub-symptom level can hold things back significantly,... that's why I add them in regularly,.. that, and they need to be well chelated to stay stable and available, which can be lost lingering around for long in-pot,... I've started using Ful-Power and like it as well, it's all fulvic acid, low molecular weight so it can be taken right into the plant unlike EDTA, etc.,...even humic acid which is far larger,... these are chelating agents as well BTW,....