Fauna Marin UltraLith System Basics

[Dark Lord Coral]

How does Ultralith work?
Ultralith is a special kind of Zeolite, specifically chosen to reduce nutrients in reef tanks. But it is not just the Zeolite itself; it is the whole new method to maintain extremely low nutrient levels in marine aquaria.
Our filtration system is characterized by its simplicity. It’s not exclusively thought to produce pastel-coloured SPS corals but for general filtration and water purification as well.
Filtration with the Ultralith System can enhance the natural coloration of all corals.
It’s also suitable for maintaining water the quality in tanks, which are set up for keeping non-photosynthetic corals.
Combined with our special food (UltraBak and Ultramin S), Ultralith is a simple and safe method to keep even the most delicate and sensitive animals.

What is the Ultralith / Zeolite System?
The name “Zeolite” goes back to the greek words “zeo” (boiling) and “lithos” (stone). Upon heating, these minerals appear to be boiling.

Zeolites are minerals and consist mostly of silica and aluminium plus other elements like Sodium, Potassium, Iron, and Manganese. The most interesting feature of Zeolites is their crystal structure. You can think of it as a sponge with many small and large holes. Large and small should be seen in perspective of the scale, the small holes have the size of single molecules, about one billionth of a meter. The size of these holes depends on the chemical composition of the mineral. There are hundreds of different Zeolites known in nature and also many different synthetic Zeolites, Ultralith is a natural Zeolite. What makes these minerals so special is their ability to absorb specific compounds. Which compound is absorbed depends on the size and shape of the holes in the crystal structure, which is depending on the chemical composition. Therefore, depending on their composition Zeolites preferentially absorb different compounds. Ultralith is specifically chosen to absorb ammonium (NH4+).

However, thinking of Zeolites just as absorbers is a bit oversimplified. They are actually ion-exchangers. The holes to which a compound binds are not empty but rather filled with sodium or potassium. As soon as a preferred compound is available, another compound, usually sodium and potassium, is given off and the compound will be absorbed. This reaction, the replacement of one ion for another ion, is called ion-exchange. In marine aquaria the liberation of sodium or potassium and therefore the resulting ionic imbalance is negligible as they are major constituents of seawater anyways.

The absorption of ammonium is just one half of the story. The other half is where the biology comes in. As already mentioned, zeolites have a very porous structure; under the microscope they look almost like a sponge. The larger holes are much bigger than the small ones, about a thousand times bigger. This porous structure creates a large surface area for bacteria to settle on. As the ammonium is adsorbed by the crystal structure, the bacteria living on the Zeolite get their food delivered to their doorstep.
The overall reaction that takes place in a Zeolite filter is the removal of ammonium and its conversion into nitrogen gas, which goes off into the atmosphere. The removal of ammonium takes place in three steps, 1. Absorption of ammonium, 2. Oxidation of ammonium, 3. Denitrification.

1) As already explained, the ammonium will be adsorbed onto the surface of the mineral due to an ion-exchange process.
2) At the surface of each mineral grain, oxygen is still available. Here the ammonium is oxidised by autotrophic bacteria to nitrate according to the following formula
NH4+ + O2 + 3OH- = NO32- + 2 H2O
This process consumes oxygen, thereby creating an anoxic environment inside the mineral grains. If this would be the only process that occurs in a Zeolite filter such a system would actually produce nitrate, and its use for aquaria would be rather limited.
3) Deeper inside the mineral grain, heterotrophic bacteria will consume the nitrate that is produced in the outer layer. This process is called denitrification, and occurs in two steps, from nitrate to nitrite, and further to Nitrogen gas. The overall formula for both processes is given below
5CH2O + 4 NO32- = 4 HCO3- + CO2 + 3 H20 + 2 N2
Because this process is carried out by heterotrophic bacteria, they need to be fed with a suitable carbon source such as UltraBak.

But Zeolites can even do another trick! Inside the Zeolite filter, there is a small but constant abrasion of the material, which contains a lot of aluminium. These tiny particles bind phosphate. By leading the outflow of the Zeolite filter into the protein skimmer the abrasion is skimmed off, thereby removing phosphates from the aquarium.

The feeding of the bacteria substantially increases the bacterial biomass inside the filter, which again results in a binding of phosphate. Dead bacteria will either be removed by the skimmer or serve as food to some animals, especially filter feeders. Eventually the Zeolites will be clogged up by the bacteria. This is the reason why the material has to be exchanged regularly.