Joe, you are going to buy more than you need because of package sizes. you're
gonna throw away the excess anyway, unless you try to save it for several
years, and it is cheap enough not to worry about it.

with the singular exception of "Rob" you are all a bunch of frickin'
idiots.

Well, I can't argue with that. (Except I'm not so sure about Rob.)

mix the powder in water until it doesn't mix anymore,
and then add a bit more water. done.

I'm sure that would work fine, but in my limited and totally unscientific
experience, a saturated solution is stronger than it needs to be to clean
the boat. All I need is enough. Any more than that is, well, more than
enough.