- Provides surface area for the colonization of bacteria to help purify your reef tank
- Reduces the peak nitrite loads better
If by Bak Pak you are referring to the PR skimmer you will not want to place media in the compartment necessarily. In most cases this can be used in a hang on back filter or in sump for added surface area. In most cases 1 L will be plenty! Feel free to let us know if you have any further questions!