"I add 50ppm when I add, this works out to 0.19 gram per gallon"
So, with some math: 0.19g x 5 gal = .95 g/5 gal, and if (1) tab (of what I purchased) = 550 mg, then
550 mg x 2 tablets = 1100 mg = 1.1g. Then 1.1 g - .95 g = .15 g extra if using 2 tabs, so -
Use slightly less that (2) tabs to...