You could also substitute solution grade sulfate of potash at the same rate, but note that it is harder to get into solution and 1 lb is soluble in 10 gallons not like the potassium nitrate where 1 lb will dissolve in 1 gallon.
They who can give up essential liberty to obtain a little temporary safety, deserve neither liberty nor safety.
Benjamin Franklin 1775
Sell not virtue to purchase wealth, nor Liberty to purchase power.
Benjamin Franklin Poor Richard's Almanac1738