What is a KZ system?

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The KZ or Korallen Zucht system is growing popular with reefkeepers. Jake Adams reveals what it is and how it works.

KZ stands for Korallen-Zucht, the German manufacturer which introduced the ZEOvit system of products to try to achieve oligotrophic (very low nutrient) water conditions, primarily for the care of SPS corals.

Although there is a misconception that an aquarium using ZEOvit is very low in nutrients these types of oligotrophic aquaria actually have plenty of nutrients, but these are tightly cycled within the tank.

Instead of having nutrients freely available in the water as phosphorus or nitrogen, a similar amount of nutrients is present in bacterioplankton which are a source of nutrition for the corals but not for undesirable algaes or the zooxanthellae which mask coral colour.

The KZ system is very effective at producing SPS corals with brilliant and sometimes pastel colours, but the technique requires careful attention to detail and is not recommended for novice coral keepers.

Some elements of the KZ/ZEOvit system can be applied to other aquaria, but all enthusiasts considering this type of aquarium method are urged to do thorough research about the pros and cons of ZEOvit before trying it out.

This item was first published in the September 2009 issue of Practical Fishkeeping magazine. It may not be reproduced without written permission.