| We've all seen salt water aquariums in books and on | | | | environment with a good supply of oxygen. The |
| the internet as well as in our homes. They come in all | | | | bacteria mentioned above operate in an oxygen rich |
| sorts of sizes and shapes, some being enormous, | | | | environment. |
| then all the way down in size to a nano aquarium. | | | | If an aquarist with our example, a canister filter, |
| Whatever size they are and whether they are fish | | | | wants to continue and deal with the nitrate, then |
| only or reef, they rely on nature's life support | | | | another filter needs to be set up for this. |
| system, the nitrogen cycle. | | | | The aquarist who has used the other example, 'live' |
| Any aquarist needs to basically understand the | | | | rock, need just let nature continue. |
| nitrogen cycle. There is no requirement to become a | | | | It is in fact best to keep nitrate at low levels, |
| scientist, just know what is going on. Then the | | | | particularly with corals but not exclusively so. The |
| dangers of stressing the aquarium will be better | | | | natural nitrate reduction process is known as |
| realized (as an example overfeeding, perhaps the | | | | denitrification. Bacteria once again form a colony, but |
| main problem with fledgling aquarists?). | | | | the environment they need is one very low in |
| All the aquarist needs to do is provide the correct | | | | oxygen. This is called an anaerobic environment. As |
| environment for the nitrogen cycle to function. This | | | | oxygen is mainly absent, the bacteria utilize the |
| can be done in several ways that will not be gone | | | | nitrate. In the process the nitrate is transformed into |
| into here....except to point out that the nitrogen cycle | | | | nitrogen gas. The nitrogen gas is released from the |
| can reach its full function with some filtration | | | | aquarium at the water surface. |
| methods and only partially reach it with others. As an | | | | There are other ways to remove nitrates (for |
| example, full function can be reached with 'live' rock | | | | example algae) but if the full natural cycle can be |
| and partial function can be reached with a canister | | | | achieved then this is the best. |
| filter. | | | | As can be seen, our example the canister filter is |
| So, how does it work? The following is very | | | | unable to deal with nitrate as the environment is |
| simplified. | | | | totally oxygen rich. To deal with nitrate, a further |
| As part of normal aquarium life, livestock put waste | | | | special nitrate filter will need to be employed. Or, if |
| into the seawater. In addition there is breakdown of | | | | nitrates are not too high, water changes may be |
| other items such as algae which has died and similar. | | | | sufficient. |
| On top of that the livestock need food which is | | | | 'Live' rock (in sufficient quantity, good condition, and |
| provided in the main by the aquarist. All of these will | | | | with acceptable water circulation) can deal with |
| produce ammonia which is toxic. Left unchecked, | | | | ammonia, nitrite and nitrate. The bacteria live on and |
| ammonia will kill our livestock. | | | | within the rock. |
| Provided a proper environment has been provided, | | | | There are filtration methods other than the two |
| nature comes to the rescue. A colony of bacteria | | | | examples given. ('Live' rock is however considered to |
| (Nitrosomas) develop and they transform the | | | | be the best, and can be supplemented by a DSB |
| ammonia into nitrite. The toxic ammonia has been | | | | (deep sand bed)). Whatever the filtration method |
| dealt with but it has been converted to another toxin | | | | employed, it must be pointed out that there are limits |
| which is nearly as detrimental to livestock. Again, | | | | that any filter can deal with. So don't overfeed. Don't |
| another colony of bacteria (Nitrobacter) transform | | | | overstock (resist the "one more fish" temptation |
| the nitrite into nitrate. Now we are getting | | | | unless you are sure your stocking level will take it). |
| somewhere, nitrate is nowhere near as toxic as | | | | Also be willing to carry out water quality tests. If the |
| nitrite. Depending what they are, generally livestock | | | | aquarium is new, allow time for the bacteria colonies |
| can stand fairly high but varying concentrations of | | | | to build, or for the 'live' rock to settle and 'adjust'. |
| nitrate. | | | | Next time you sit and view your seawater aquarium, |
| It is at this point that the nitrogen cycle has gone as | | | | think of the bacteria, nature's engines, working for |
| far as it can in the example given above, the canister | | | | you. |
| filter. All the bacteria have required is a suitable | | | | |