I used to have the yellow pale leaves that you are experiencing and after dosing K, it went away in a couple days.
Not sure if it's accurate but here is how I dose K, assuming no K is being used.
I mix 250ml of water with 5 tsps of K2S04 for my 75g resulting in .19ppm in each ml of solution.
I add about 10ml each day and after 1 week I get about 13.3ppm. On day 7, I do a 50% water change, which results in 6.65ppm. (This is the part I'm not sure of, but it works for me.) The next week I continue to dose everyday, which will then bring me to 19.95ppm. Do another 50% water change and I get 9.98ppm. The 3rd week I do not need to dose every day, but rather each other day, never exceeding 20ppm. This is just the pattern I use, it doesn't account for the PMDD I also add.
Btw, how do you calculate your Iron levels to be .1ppm using both Flourish Iron and CSM+B?