Many times, I have seen this question being asked by reefers especially those who are new to the hobby. Well, if you were one of them, there is no need to be embarrassed - it is a most valid, if not the most important, question in this hobby. Why, because when it comes to reefing, BACTERIA IS EVERYTHING! My objective here is to help shed some light to this question.
I don't know if any of you out there has done scuba diving or snorkelling before, but I used to dive quite a bit when I was younger. Believe me, in all my dives, I have never once seen a skimmer, nor a de-nitrator, nor a phosphate reactor in the sea. Now, we all know that these are some of the most important equipments in our saltwater aquariums. Without them, water quality will deteriorate rapidly, resulting in livestock deaths. So without any of these equipments, how do corals and fishes stay alive in the sea? The answer - BACTERIA.
In the seas, bacteria exist naturally and they are responsible for keeping sea water in good condition for live-stocks of all sorts to survive. Good water quality means a low level of un-dissolved and dissolved organic matters but more importantly, the absence of toxic substances such as ammonia (NH3/NH4) and nitrite (NO2). Good water quality also means low levels of nitrate (NO3) and phosphate (PO4) for the abundance of these substances has detrimental effects on most living creatures in the reef.
Phosphate is mostly introduced through animal waste but they are also washed down from the land, into streams and rivers, and eventually into the seas. Phosphate pollution is much less measurable than nitrates and is easily removed by the large quantities of algae in the seas. Nitrate on the other hand, is removed through a sequence of chemical reactions where bacterium plays a key role. This sequence of chemical reactions is called 'The Nitrogen Cycle' (sorry, couldn't insert diagram). It explains how bacteria help to get rid of undesired chemicals.
fish & invertebrates excretion, algae decay => ammonia (NH3 & NH4)
=> nitrite (NO2) => nitrate (NO3)
=> nitrogen gas
=> nitrate taken up by algae => algae consume by fishes
Ammonia is inevitably introduced through animal secretion and decaying algae as well as other organic matters. A strain of bacteria, under the class commonly known as aerobic or nitrifying bacteria, feeds on ammonia and converts it into nitrite. A second strain of nitrifying bacteria then feeds on nitrite and converts it into harmless nitrate. Some of this nitrate will be absorbed by algae as nitrate is also food to plants. But unless there is a great abundance of algae, much of this nitrate will remain in the water. So this is where the second class of bacteria comes in. This class of bacteria is commonly known as anaerobic or de-nitrifying bacteria. Unlike aerobic bacteria, they live in oxygen-deprived environment such as deep sand beds and does the opposite of what aerobic bacteria do - it feeds on nitrate and convert nitrate into harmless nitrogen gas. Algae are in turn fed on by fishes and so the cycle repeats itself. It is a complete ecological system. No special equipment is required.
Therefore, in the absence of aerobic bacteria, fishes and invertebrates will surely die from ammonia and nitrite poisoning. And in the absence of anaerobic bacteria, nitrate pollution will be very high and fishes and invertebrates will live under great stress. Fishes will stop growing and invertebrates will refuse to extend their polyps and both will loose their coloration.
Dosing Bacteria
This is not a must but it will surely save you a lot of pain and money. Bacteria dosing is especially helpful when you are starting a new tank. If you are using marine salt mix, you should know that it does not contain bacteria. If you are using natural sea water, you can never know its quality for sure or how much of its original bacteria are still alive since bacteria fatality is very high during transportation and storage. But either way, you will have to wait for weeks and even months for the tank to mature (meaning, for enough bacteria to grow naturally to form a large enough bacteria culture). The alternative is to introduce the bacteria artificially through dosing commercially available bacteria products. By dosing bacteria, you can cut down the cycling time drastically to a matter of days. What's more, the risk of losing fishes and invertebrates can be greatly reduced, making the experience of starting a new tank a less painful one.
But after your tank has gone through the maturation period, is it still necessary to dose bacteria? Again, this is not a must but it will surely save you a lot of money and pain. The general misconception is that bacterium is all powerful and never dies. It is only natural for us to assume that since whenever we are sick from bacterial infection, bacteria don't seem to go away until we use antibiotics on them. This is however far from the truth - bacterium is in fact a very fragile life form. According to scientists, most bacteria do not survive for more than 15 minutes outside laboratory conditions. And each time water circulation in your aquarium system stops for 30 minutes, as much as one third of the bacteria population can be wiped out. Bacteria can also die from diseases, poisoning and the lack of suitable food. So while the bacteria in your aquarium system are multiplying, they may also be dying at the same time. So if a large proportion of the bacteria population gets wiped off for whatever reasons, toxic ammonia and nitrate will build up very rapidly resulting in massive life-stock deaths. It is therefore wise to dose bacteria on a regular basis. This is to ensure there is always a sizeable bacteria culture in your aquarium system to get rid of toxic ammonia and nitrite. Besides, bacteria also helps to keep your aquarium water clear by feeding on un-consumed food and livestock waste. You can never over-dose bacteria.
Quote
Reefkeeping Online Magazine
August 2009
Volume 8, Issue 4
Paul Baldassano's Reef - 40 Years in the Making
A Different Technique
There is one more non-typical thing that I do that some may consider either risky or just useless. I mentioned above that I add bacteria from the sea to my tank. I feel bacteria are the most overlooked aspect of this hobby, and are vital to a healthy, long-lived tank. Bacteria cover everything in our tanks, but are they the correct bacteria for our purposes? Probably not. Bacteria enter our tanks in a number of various ways. Every time we put our hands into the water, we add bacteria. When we add fish, corals, rock or food, we add bacteria. The bacteria on the rocks and fish were at one time in the sea and "some" of those bacteria are the correct bacteria for our needs. But eventually, that bacteria will stop reproducing and will be outnumbered or outcompeted by other bacteria that may not be dangerous but do not necessarily help complete the nitrogen cycle. Why do so many people change so much water and still have nitrates? If we had the correct numbers and types of bacteria, we would never have to change water just to lower nitrates; the bacteria do that for us for free. I have found that by adding bacteria from the sea a few times a year, my reef stays healthy. I have no scientific data on this theory, but I do have a 40-year-old tank with an undergravel filter and no nitrates.
Happy Reefing!
Sam
+65-97470599
