Apr 24, 2002, 11:10 AM
Post #7 of 28
In reference to the explanations above it is important, when you first construct your pond and filter to ease the filter in gently. You have your pond filled with fresh water that you have added your de-chlorine solution to. Your filter is up and running, the water is crystal clear as you have only just put it in. You take some readings, PH 7.5, ammonia 0, Nitrite 0, Nitrate 0. Every thing looks good, so you can now add all your koi into the pond as the water is perfect right ?. Wrong !!!!. The filter in not yet mature. Lets compare it to a weight lifter in the Olympics. Does he walk up to that stage and say, ok put all the weights on I’m sure I can lift it ?. No he doesn’t he starts with a light weight and works his way up. This is how you need to treat your filter. You should start with your filter running for 2 weeks, then add 2 – 3 fish per week, taking water reading every few days. If you find that your ammonia levels are high but these are not much traces of Nitrite and Nitrate, then the Nitrosomonas in your filter have not developed yet. If you find that your Ammonia are fairly ok but your Nitrate is sky high, then your nitrospira marina have not developed yet. Just for reference: Ammonia is three times more toxic than Nitrite.
Lets have a closer look at the cycle. Please note that time scales can never be accurate due to the impossibility to determine how quickly a filter take to mature. Below is just a rough example of the process.
Day 1 - 10
Note the first 10 days on the above graph. Ammonia begins a rapid rise up to lethal levels and then drops dramatically to close to a zero level. The replication of the bacteria determine this rise and fall. Since they replicate geometrically, the hypothetical first "bug" becomes 2 in 8 hours, then 4 (16 hours) then 16 (24 hours) the 32 (32 hours) then 64 (40 hours) and so on..... It takes about ten days in relatively ideal conditions for the bacterial to replicate to population where all the ammonia produced within the aquarium is immediately reduced to nitrite (please note that this is based on 1 pond that was tested and will not be the same for every pond). What is shown on the graph is the sudden drop of ammonia concentration slightly after the 10 day maximum.
Day 10 – 21
The next 21 days, after the ammonia spike drops to minimal, now show a low to zero level of ammonia residue, but a steadily increasing concentration of nitrite, rising much higher in concentration than the ammonia graph, about double in fact. Nitrite is toxic, but not as toxic as ammonia, thus the simple fact that the concentration can rise so high without a total loss of fish. As nitrite becomes more evident, so do the populations of nitrospira marina removing the nitrite from the system and changing it into nitrate [and energy for the bacteria]. As the populations grow, they gradually become able to reduce nitrite as soon as it is created by nitrosomonas acting on ammonia production. After 21 days from the beginning of nitrite build-ups the spike falls rapidly to the low levels of the graph. From there the nitrate levles start to rise over time.
There is a problem with the above simplistic view, Mother Nature has thrown a curve into the straightforward Nitrogen Cycle reviewed above. The bacteria that reduces nitrite to nitrate, nitrospira marina is inhibited by a free concentration of ammonia in the water. This is the reason that the nitrospira marina population is essentially kept at a zero level until day ten when the ammonia spike reaches the minimum level. Once the ammonia inhibition is removed, then (and only then) nitrospira marina can begin to replicate. They are also lithotrophic so they require the same things that nitrosomonas require, oxygen, their food source and clean hard places to attach and populate.
After Day 31
Once the nitrite is removed as fast as it is produced by nitrosomonas, the final by-product of the Nitrogen Cycle is nitrate. It is a compound which is not easily reduced any further by aerobic bacteria. Because of this, the nitrate levels begin to slowly rise and continue to build over the rest of the life of the pond. The best way to get rid of nitrate is simply to practice proper water maintenance procedures. With regular water changes, nitrate is diluted, removing water with high nitrate concentrations and replacing it with low nitrate conditioned tap water is one of the most effective ongoing ways to eliminate nitrate. A second method is by using a vegetation filter, the plant life in this filter use Nitrate as a form of fertilise and give back Oxygen into the water. If you have this then think of how much time you can save by all of those water changes. The last way which has been tried in various ways by members of this forum, is the trickle tower. For more information on this see the hot topic list on the main homepage.
Again I hope I have helped someone by this explanation, comments, additions (or corrections in johnson's case ) agin more than welcome.