I don't see any weight numbers on the photo of an HC110 bottle I have in hand. Any chance you are confusing fluid ounces with weight ounces?

I expect that the best way to do this would be to weigh a full bottle of HC110, then weigh an empty one and to that subtraction. Then divide the result by 473 to get the weight of each ml of concentrate. Finally, multiply that weight by 6.

I'll have to see if I have full and empty bottles in my storage area.