Instructions on a 32 oz bottle says to pour 1/3 of bottle into the pipe, is that 1/3 cup or 1/3 of bottle? What is 1/3 of 32oz?
That would be one third of the bottle. 32/3 if 10.67 ounces. I cup is 8 ounces, so you would want about 1 1/3 cups for 10.67 ounces. Odds are that "eyeballing" 1/3 of the bottle is going to accurate enough for what you are doing.
1/3 of the bottle, a little over 10 ounces
"1/3 of bottle" means one third of the bottle. 32 divided by three is just a hair under 11 ounces, or about and ounce under a cup and a half. A liquid ounce is two tablespoons, so measure out a cup and a half and put two tablespoons back in the bottle. That will get you close enough.
10.67 oz of the bottle. It does not say cup.