Yup.

Do the chlorine as instructed -- repeat dose in AM if chlorine is below 5 ppm.

If you don't see significant color change 24 hours after the first dose, increase the dose to 10 gallons in the PM. However, if your pool is vinyl, drop back to 6 gallons after you have a color change AND are are holding "dark yellow" overnight.

AND . . . except for adjusting the pH, do NOT add other chemicals. By the way, check your pH levels in the evening BEFORE you add the PM chlorine dose. Very high chlorine changes the phenol red indicator, to another indicator "chlorophenol red" which is violet purple at pH levels above 6.8.

Ben