Hi, my name is Alexander, I was born an live in Germany. Please be patient with my English, it is not perfect, I know.
I found some threads about the Zeovit products in the board. I use this method since September 2001 in my nearly 100 % SPS tank. The result of the method is impressing. The method is working fine, it is easy to apply and the components are not to cost intensive.
I am a little bit confused why some people always try to explain that this method is the same thing like dosing vodka, sugar or some other stuff like the Aqualight products (ZeoBioBac).
Dosing carbon (Vodka) to boost bacteria maybe helps to bring down PO4 and NO3. There are some reefers in Germany running this method with success, other tanks crashed. I have heard from some reefers using this method in their tanks stocked with delicate SPS corals. They had no success. The corals lost their tissue beginning at the top, also loosing their colors. I have not tested this method.
I also did some tests with sugar some years ago. Everybody telling that it really works is not genuine. Adding sugar to the tank will boost the growth of bacteria, especially red or brown slime.
The other product named in this thread (ZeoBioBac) is from a German company named Aqualight Feige. This company is specialized in freshwater which is totally different from seawater. They also offer zeolite, bacteria and a food source for the bacteria. The keynote is the same as the Zeovit system, but the ingredients are totally different.
First of all it is more than important to use a zeolite which is capable for seawater. To find this products it is very important to know what to find. There are hundred different zeolites available each one with his own attributes. The Aqualight zeolite, I tested 2 years ago, caused tissue lost from the base, also the lost of color in most of my SPS.
I also did tests in the beginning with the bacteria from Aqualight. Dosing them in the recommended quantity shows no effect. The quantities needed are absolutely improvident and to cost intensive for me. Maybe the bacteria of the Korallen-zucht products and the bacteria of Aqualight contain some equal bacteria but the concentration seems to be very different.
The last point is the food source for bacteria. Both products (Aqualight and Korallen-Zucht) contain acetic acid. To find it out we do not have to be chemicals. I also used the Aqualight product 2 years ago. I lost some fish 2 hours after adding the recommended quantity. Zeofood does not contain iron to fell PO4 !
To understand how the Zeovit method works it is necessary to consider that SPS can use nutrients as a food source. This will boost the growth of zooxanthellae. Corals can use the waste products of the algae as one of some other food sources. The corals will become dark like chocolate. If the zoox density is high, the natural color of the corals is superpose and we can not see the real coloration.
In a nutrient poor environment SPS are not necessary to use the same quantity of nutrients as food source. They need other elements to kept alive. These elements are contained in the Zeofood and in some other products sold by Korallen-Zucht. All the elements contained in this products are not theoretically mixed. They did copious tests for many years in their own tanks containing also very delicate corals. Visit their homepage, there are a lot of pictures proofing that the system works great. They also run a shop, I only can recommend visiting them if you do your next trip to Europe.
It is also necessary to bring good coloration to the SPS with PO4 absorbers and trace elements, but the look of the colors and the tissue is very different. If the Zeovit method is used correctly, you can not differ if the corals is located in a tank or in the sea.
Constant water change, strong skimming and a good light source provided to the Zeovit method is not a secret to increase coloration and this is practiced with a lot of methods.
I do not want to denigrate other ways, but these are my practical, personal experiences.
Hope this brings some clarity.
Alexander