This is something that should be addressed by the person's Dr. Potassium is potentially deadly in too high of doses (it's what they use to stop the heart in lethal injections after all) Anyone taking potassium supplements should have their levels tested before starting them and find out for sure if it is OK and what the safe amount *for them* would be.
potassium has a substantial effect on BP and other related things, you need to talk to your Dr before taking anything that was not prescribed or recommended to you by your Dr. Just because it's available over the counter doesn't mean it's innocuous
Potassium of 2,000 to 3,000 milligrams is safe per day for a hemodialysis patient. Such a patient should take it easy and take low amounts potassium. The quantity is according to The American Association of Kidney Patients. You need to see a doctor and consult for more details.