I am working with body wash products and there is a problem happening with the mixing process. I use a 5000-liter tank to mix all the liquid materials including water, surfactant and preservatives. When I use a vacuum pump to add liquid materials from the bottom of tank, the content of preservative is A (g/100g). However, when I add them throug hthe top of tank, the content of preservative decreases. I am really confused because everything (amount of materials, equipment, machines) used in 2 ways is the same. And I have no idea why the content decreases. Please share your opinion. Thank you.
It sounds like your additives are in suspension not solution. Like a fruit juice drink. You take orange powder stir it and it makes a nice drink. Leave it several hours without drinking it and you will return to a glass of water with orange stuff at the bottom. If the solution is not continually stirred the additives will sink to the bottom.