Only a couple of notes/ corrections to B=C's advice:

I'm assuming your pool is a vinyl above-ground with that gallonage. With a vinyl pool a Tot Alk of 180 is FINE--don't worry about it. A hardness of 400 is high, but don't worry about that either until it hits 500ppm.

I don't want to steal this phrase but I don't know who deserves credit - 'Shock is a verb not a noun'.
That's probably me, but I'm sure Ben and some of the other moderators and other long-term posters have said something similar.