If you want to reduce your base nutes and add something to increase K only, then use potassium sulfate...BOOM homemade terpinator. Those monopotassium phosphate bloom boosters are just the goofiest thing, how long will it take for the cannabis fertilizer industry to stop forcing useless amounts of phosphorus on us? Totally agree with seaweed, I run it through every grow, one of the best flavor enhancers along with all the other benefits. Epsom salt is a reasonable addition for as well-don't need much, I'm talking 1/4 teaspoon per 3 gallons (1/4 teaspoon per gallon if you're actually deficient in mg). A little extra sulfur in the form of epsom salts or potassium sulfate goes a long way towards making dank buds.