Add 1/2 gallon at a time -- on your pool that will be about 1.5 ppm. If you have 0.0 chlorine, and CYA = 90, try to get at least (3) 1/2 gallon doses in tonight. Add them via the skimmer, and wait 30 minutes between doses.

By the way, if / when you add acid to the pool, do NOT add it via the skimmer! Doing so will take metals OFF the filter and put them BACK into the pool!