Subject: Nitrate - Long post
There does seem to be a lot of unnecessary concern of nitrate levels expressed by people on this list for relatively low levels of nitrate.
Nitrate is the end product of the ammonia cycle ("The Nitrogen Cycle") that occurs in every tank.
There is no easy way to naturally remove nitrate without the use of a setup that uses anaerobic bacteria to reduce nitrate to its components. The usual method of deal with nitrate is water changes (25% PWC's) and the addition of live plants, which includes algal growth.
At what level should one really become concerned about the level of nitrates in the aquarium. A level of 1000 ppm is definitely a concern, since everything dies. So we need to go lower than that. 500 ppm is still of definite concern. Many animals and plants will die at this level also, but some will live, though not well, as they will be subject to long-term effects of nitrate, such as hole-in-head disease and the erosion of the lateral line. Some plants also will not survive this level of nitrates.
At 200 ppm, the effects of nitrate will be more long term than immediate. Again, we would be looking at such things as later line disease and hole-in-head as a result. Going lower will help reduce the effects. At 150 ppm, again, the effects are long term. Going even lower, long term effects are still present.
Ideally, one would wish to reduce nitrate levels to less than 20 ppm, but immediate action is not called for until you reach a number of more than 150 ppm. Please do note that figures for a marine (salt water) aquarium are very much different, and action is called for when nitrate is measured in the single digits of ppm. In a marine environment, it is possible to reduce nitrates to immeasurable levels through the use of foam fractioners, which do not work well in fresh water.
So, you notice that your nitrates are rising, or at a high level. One can simply panic and do immediate large water changes (or a series of 3-4 24% PWC's) to reduce the level of nitrates. However, doing this fails to discover and remedy the core cause of the high level of nitrates. Unless you are getting reading over 150 ppm of nitrate, you do have some time to do investigative work to discover and remedy the cause of the nitrates, while your regular water changes (25% PWC's) should help you reduce the level.
Where does nitrate come from? Nitrate is the end product of the ammonia cycle ("The Nitrogen Cycle") as we follow it in the aquarium. Ammonia is produced as a waste product by the animals you have living in your tank. It can also be produced by dead and decaying animals and plants as well as food added to the aquarium. If you are using fertilizer for your plants, this may also be a source of ammonia. You need to reduce the sources of ammonia. Feeding less will help reduce the level. Most of us feed our fish too well. A day of fasting may help the health of your fish, as well as reducing the amount fed each day. Raising fry is a whole other ball of wax, which I will not be covering here, but to get quick growth you do want to ensure they are well fed. If there is left over food when you are feeding, you will need to reduce the amount of food you give to your fish, until there is no left-overs in the tank. Until this is remedied, you will want to wait a while after feeding the fish, then siphon off the left-overs.
If you are fertilizing your live plants, you will want to reduce or stop the fertilization of the plants or start adding only the trace elements your plants may need for good growth and avoid a fertilizer that contain nitrogenous products.
Also look for and remove any dead materials from your aquarium. Likely, if this is a fish, you'll do it rather rapidly. If it is plant material, then you will need to, perhaps, do this on a daily basis. Algae poses a particular problem. Removal of algae will reduce the capacity of your aquarium to remove nitrates, but then, it is also difficult to know when to remove it because it may be dead or simply another form of algae. It may be best to follow your aesthetic sense and remove what does not appeal to you, and remove any that is not green. Those of you that have snails in your aquarium are faced with a sometimes difficult decision--is the snail dead or is it alive? Tough to tell sometimes. However, if you have a nitrate problem, it may be well to take the conservative course of action and remove any snails you have doubts about, either to dispose of or to place in another environment. (You can always do the smell test on a snail. If it smells rotten, it's probably dead but you can put it in another container with some of your tank water if you want to be cautious.)
Throughout this entire process, you will need to keep an eye on the progress you are making. Go back to daily testing of your ammonia, nitrite and nitrate levels. Also test your tap water, which could be another source of nitrates in your aquarium. The EPA has a regulation that states that drinking water should not contain more than 10 ppm of nitrate. However, from reports of aquarist's around the country, not all water companies are meeting this requirement. Also, if you are using well water, your nitrates may be high, especially when the aquifer is in agricultural parts of the country. Our well fertilized lawns and gardens can also have an effect on the nitrate level of aquifers, but most research has pointed to agriculture as a large culprit. If your water is starting with unacceptable levels of nitrate, you will need to look into means to reduce the nitrate before the water reaches the aquarium. This is usually done with chemical adsorption products.
If your nitrate level still does not lower after doing all this, you will need to look at some other aspects of your aquarium. I have mentioned live plants in this discussion, but I am aware that not all people utilize live plants in their aquariums. There may be practical reasons for this, like the vegetarian habits of your fish prevent the growth of plant s to any great extent, and may reduce the number of plants you have, your fish may be diggers that uproot plants, etc. Your tank may simply be overcrowded with fish, and be overloading the biological processes that would normally handle such situations. In the former situation, you may want to utilize the marine idea of a refugarium, where there is a separate tank that water flows through that has plants to pull out the "bad stuff" from the water, with water from the main tank run through the filtration system into the refugarium and back into the main tank. You may also wish to investigate plants that may be immune to the predation of your fish. As for overcrowding, well, you simply need to reduce the numbers of fish that are present in the tank. You may set up more aquariums to house them or give them to friends who would like them. You may even be able to bring them back to you LFS for credit.
Another source may be a decoration that has recently been added to your tank that is leaching substances into your water as it 'cures' in your tank. Removal of this object will show a quick and drastic reduction with your next water change. Should this be the case, you'll need to either cure the item outside the tank, or do without it inside the tank.
Also, not usual, but, perhaps not as unusual as we may like to think, there may be an outside force acting upon the tank, like something some one has added to the tank without your knowledge. One of the kids could have put something in the tank without your knowledge and you may never know if the youngin' expects they'll get a punishment for admitting it or an adult at a party may have added something just o see what the fish will do. This kind of thing can be the devil to track down, and the influence will abate with time.
What ever you need to do, don't panic. Take things slowly and try to identify the cause of the problem. Your fish will allow you time to fix things. Should you be keeping marine fish, well, as I mentioned earlier, we are in a whole other ballpark there, and you may need to take more rapid action to avoid losing animals. Marine animals have less a tolerance for nitrate than freshwater do, and I would advise you to find a guru near you that can be of assistance. I'm not a marine person, nor do I play one on TV, and do not claim to have any special knowledge of marine topics.
Don't buy into any 'magic' cures for what ails your tank. They may do more harm than good.
Thank you for your patience reading this long, and somewhat involved post.
\\ Steve //
Here is a follow-up email from Steve to me.
I've been out of town since before you posted this, and have just returned today. I do need to emphasize that there are some fish, such as those of the _Apistogramma_genus (at least some have been placed in the _Microgeophagus_genus now, I think), that are fairly intolerant of nitrates of any level.
One needs to check the literature available on these, and any other species of fish to determine what levels of nitrate they can stand. I do not believe this was emphasized in my original post properly.
The original post was merely meant to ease some people's fears, and therefore need to do something immediately, about nitrate levels that may be considered to be too high. Rapid changes in water chemistry can be more dangerous to the fish than the condition you are trying to correct.
Generally, if the nitrates are out of whack, it did not happen overnight, but was a gradual rise over a period of time. The correction should lead to a gradual downward trend over time. If you are keeping fish that are sensitive to even minimal levels of nitrate, such as the rams mentioned above, you may need to react quickly to change the level, and try to save as many as you can, but generally, a slow and considered approach is best for all involved.
\\ Steve //
BIG THANKS to Steve for this long article on Nitrates and his follow-up clarification.
EDIT added August 23, 2009.
Here is another good article that I found after looking at a web page that file://steve// posted to the AquaticLife Yahoo Group, which further talks about the effects of nitrates on our fish.
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