[erikages]

Yipes! Never heard of it, but if ZEObak has this stuff in it, no wonder you only need 1 drop per 25 gallons. But this seems to be a chemical compound rather than "biological." ZEObak literature suggests that it's made up of bio. materials.

Here's a blurb:

The essential microorganism solution for a healthy, well-balanced and efficient bacterial fauna in a tank.

ZEObak contains several bacterial strains, and is best used in combination with ZEOfood and ZEOstart while building up bacteria plankton that is absorbed by many corals.

Contains several bacterial strains that form a chain to reduce unwanted substances improving water quality and clarity.