Continued from page 6
How is the Culturing Done?
Start by adding small amounts of sand that is not live into the tank, and add it straight to the bottom. Let it sit there and make sure that you stir it from time to time to ensure that no dead spots or areas are formed. The stirring can be done with a small wooden stick (such as the ones used in gardens to grow certain vegetables on) or with a piece of acrylic rod.
In order to avoid clouding up the aquarium too much (some will occur and is unavoidable), put the "dead" sand in a plastic bag, lower the bag to the bottom of the tank, turn the bag over and let all the sand fall out of it and settle on the bottom of the aquarium.
It appears from experience, that it is pretty safe to add about 1/4 inch of non-live sand to the tank and let it sit there at the bottom. As time goes by, bacteria of the desirable type will start to colonize the sand (as they do in and on anything that is present in the tank). The bacteria referred to are the ones mentioned above.
Where do these bacteria come from? Since the tank always contains dissolved and non-dissolved organic matter, some of it will work its way into the sand and start to decay. This will give rise to ammonia. The presence of ammonia gives rise to the appearance of Nitrosomonas. The latter turn the ammonia into nitrite. When nitrite is present, Nitrobacter soon appear spontaneously, turning the nitrite into nitrate. This whole process normally takes about 28 days (at least in an aquarium where none of these bacteria are present).
Since the aquarium to which we are adding the dead sand already has a biological filter that is maintaining the tank, it is easy for some of these existing bacteria to multiply really fast and immediately neutralize the ammonia and the nitrite that is being generated in the sand. This is the process by which the sand becomes live. Now it is populated by bacteria and microbial life. How long the process takes is variable, as explained earlier.
The hobbyist really does not have to do anything, the organic material is always present and some will work its way, naturally into the sand. As soon as that happens, decay will start and the process described above starts to take place. The ensuing result is that the sand becomes live.
Where does the organic material come from? Below are but just a few examples and sources:
- uneaten food from over feeding
- feces that contain undigested or partially digested food
- small algae that died
- microscopic algae that die off
- bacterial die off
- sludge produced in the aquarium
- slime from fish
- slime from invertebrates
- animalcules that lived on the rocks and died
- and so on
Hobbyists can monitor what is happening with the sand by measuring ammonia and nitrite levels in the water. When small amounts of one or both are present, we do not want to add more sand. Indeed, doing so would only increase the amount of these toxic and noxious elements. More decay would take place which could even create an ideal environment for anaerobic activity by covering a layer where aerobic decay is taking place with more sand.
When a layer of sand where aerobic activity is taking place is isolated from its oxygen supply, that aerobic decay could turn into anaerobic decomposition. This would result in the formation of by-products of such decay, all of which are toxic (hydrogen sulfide being the better know one and the one that would, more than likely, be produced). H2S diffuses into the water extremely rapidly and affects both corals and fish negatively. A tad too much of it and you have a die-off.
This would create a great deal of stress for the animals and, if a lot of it were to be released in the water, fish may die and corals may be affected as well. The lesson to be learned is, therefore, that one cannot add more sand, unless the tank's water is totally ammonia and nitrite free. Make sure when you decide to culture live sand in your aquarium, that you have a good and recent ammonia and also a nitrite test available so you can perform all the testing you need to perform.
Keep in mind that when you add dead sand to the tank, ammonia will not appear immediately but that it may take several days before it does. Testing right after adding sand will not yield accurate results. One needs to wait a few days to determine that all biological filtration is working properly, and that enough bacteria are being formed in the sand (that is now becoming Live) and in and on the Live Rock that is already in the tank. We know this is so when ammonia and nitrite are neutralized and turned into nitrate. It would be a good idea to have a nitrate test as well. Monitoring nitrate levels will indicate when the live sand passes from stage 1 (normal biological filtration) to stages 1 and 2 (in the second stage, nitrate is being removed from the system as well).
If other biological filtration devices are being used, they can slowly be removed once the sand is live. This should be done slowly and carefully. Again, testing for ammonia and nitrite should be used to determine whether or not more of it can be taken out. If, for instance, you have a trickle filter that contains bio-media, do not remove all the media at once. Remove it progressively and make sure that the tank's water does not show concentrations of ammonia and or nitrite before you remove more of the media (this procedure is described in much more detail in a free article in the Library, titled: Converting ... )
When none is present, or when the concentrations that were present for some time have disappeared, one can add more dead sand. It is suggested to add another 1/4 inch on top of the existing layer and them mix the two together. The mixing is important as it will speed up the transfer of bacteria from the bottom layer that is now live, to the the sand that is being added.
When culturing live sand in an existing aquarium one does not resort to the addition of ammonium chloride. This is done only in systems where there are no animals (the outside of the tank method), as we shall see later. The reason it is done using that procedure, is to speed the whole process up. In existing aquariums this would create a great deal of stress for the animals so it is not recommended and, in fact, is to be discouraged. Stress needs to be avoided at all costs, as stress leads to animals that may become diseased, and often do.
Keep adding dead sand, and do so one quarter of an inch extra at a time, following the above procedures, and so until you have attained the sand thickness you are aiming for. Note that what we are discussing here is plain, preferably non-silica based, sand.
The method described in the article "Live Sand Update" mentioned earlier uses a mixture of different kinds of elements to achieve a sand layer that is coarser and not as subject to anaerobic activity. To get more details on how this is done you should read that article as well. It is a different method, although it still uses the same principles. The difference is in the ingredients used to make up the sand layer. Indeed, instead of using just plain sand, crushed coral and crushed shells are used as well. The article details exactly how to go about using such a mixture. In terms of making it live, after the mixture has been prepared, everything written here still applies.
The reason non-silica based sand is very strongly recommended is really simple and obvious: it avoids leachings of silicates and silicic acid into the water. If the latter occurs, brown algae or diatoms will appear in the tank. This is undesirable. Getting rid of such algae is more work. It also ends up costing money to acquire the chemical filtering media needed to remove the silicate and the silicic acid. Avoid it. Why spend time and money when you don't have to.
When buying sand make sure it is silica free! Do not buy playground sand because it usually contains large amounts of silica. The best sand is, probably, sand made from coral skeletons that have been crushed and have been crushed really fine so as to have the right size (2 mm and up) grains for the application we are dealing with. If you cannot find this particular kind, call around and find sand that is either real low in silica and is silica free.
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