Why liquid totes are not filled to the top with liquid?

Specific gravity is a measure of the density of a liquid relative to water. Both of these flasks contain fluid that each weigh 1 kg. The flask on the left is filled with 1 kg of water, and water has a specific gravity of 1.00. This means that for every 1.00 kg of water, the fluid will equal 1.00 L in volume. The flask on the right is filled with Liquid Humic 12%, and this product has a specific gravity of 1.04. To fill the flask with 1.00 kg of Liquid Humic 12%, the volume will need to be 0.96 L, as you can see by comparing the 1000 mL lines on each flask.