Nitrogen Cycle
Constantly doing water changes is for the birds; I am basically lazy so over a two-year span I learned that you don’t have to do very many water changes. You do have to set your tank up so that this is possible; use a skimmer, maintain good oxygenated water with water movement, use additives to keep water element levels correct. I only do water changes one every three months if, nitrates, salinity, or alkalinity are off and cant be corrected by use of an additive. I am not saying to use an additive to lower nitrates that is what cured live rock is for.
Why live sand?
It provides the environment for bacteria, and contains the live bacteria. Two inches of fine live sand will provide Ammonification and Nitrification. If this bed of sand becomes clogged with waste it will start Anaerobic Ammonium Oxidation and Denitrification which is not Bad like many think, but hydrogen sulfide producing bacteria can be a problem. If hydrogen sulfide gas builds up in the sand and then is released in to the water by disturbing the sand the concentration may be harmful. If the sand bed is too thick you will get Anaerobic water and hydrogen sulfide gas. So keep the (two inches of fine live sand) clean and Anaerobic water will not occur in the sand. The use of fish and invertebrates to keep the sand sifting and unclogged gets easy over time. After a few years the sand becomes clogged with fine waste and you have to replace it.
Why cured live rock?
It provides the environment for bacteria, and contains the live bacteria. In the correct amount and thickness it provides Ammonification, Nitrification, Anaerobic Ammonium Oxidation and Denitrification. Now this is the trick we want some Anaerobic water deep in the rock so the nitrates will be dinitrogenated or changed into largely inert nitrogen gas. You will see bubbles on your rock this is not air it is mostly nitrogen gas, dinitrogen gas, and a little hydrogen sulfide gas. This gas is released in a constant manner not likely to concentrate and become harmful.
Ammonification
Nitrates are the form of nitrogen most commonly assimilated by plant species, which, in turn are consumed by heterotrophs for use in compounds such as amino and nucleic acids. The remains of heterotrophs will then be decomposed into nutrient-rich organic material. Bacteria or in some cases, fungi, will convert the nitrates within the remains back into ammonia. Needs oxygenated water!
Nitrification
The conversion of ammonia to nitrates is performed primarily by soil and water-living bacteria and other nitrifying bacteria. The primary stage of nitrification, the oxidation of ammonia (NH3) is performed by bacteria such as the Nitrosomonas species, which converts ammonia to nitrites (NO2-). Other bacterial species, such as the Nitrobacter, are responsible for the oxidation of the nitrites into nitrates (NO3-). Needs oxygenated water!
Anaerobic Ammonium Oxidation
In this biological process, nitrite and ammonium are converted directly into dinitrogen gas. This process makes up a major proportion of dinitrogen conversion in the oceans. Needs Anaerobic water!
Denitrification
Denitrification is the reduction of nitrates back into the largely inert nitrogen gas (N2), completing the nitrogen cycle. This process is performed by bacterial species such as the Pseudomonas and Clostridium. Needs Anaerobic water!
You see that a little Anaerobic water can go a long way to keep the tank clean, but if not kept in check hydrogen sulfide producers can be a problem! So keep the water moving and the sand sifting, add more cured live rock if your nitrates don’t zero out and only do as many water changes as your tank needs. Use additives to keep water element levels correct.
This method can be used in combo with other filtration methods, but like I said I’m lazy.
GeoJ