What Causes High Nitrates?

[julielynn47]

What cause nitrates to be high?  My tank has been cycled since 2007 and it has not had high nitrates since then. It always reads 0 for nitrates. This morning I checked and it is reading high. Which is totally weird to me as it never reads high.
 
 

The API test kit reads somewhere between 10 and 20. It is orange, but not to the next color yet.  

I am wondering if that could have something to do with the black algae that I have been fighting. I have no idea, it is just a thought on my part.  

I read this article http/www.tfhmagazine.com/freshwater/feature-articles/keeping-up-with-nitrate.htm  and it seems to me I am already doing everything it says in it, and pretty much always have.  So I am really at a lose to know what is going on that could be causing it

I am also thinking that maybe, all this time, I have not been shaking the API number 2 bottle well enough.  I really shook the snot out of it this morning after reading so many times on this board how it settles on the bottom of the bottle really badly

 

[julielynn47]

I do weekly and sometime twice a week 50% water changes. Should I be doing more than that even?

 

[gmc1]

Is it possible that you are just doing the test correctly now.by that I mean shaking the bottle.that level of nitrates is OK.

 

[Byron]

That article is very good information.  It is especially helpful to read sensible advice on the dangers of allowing nitrates to remain at levels many still think are "safe" but are not.
 
On the API nitrate test, regent #2 needs to be shaken very well for 2 minutes (not just 30 seconds as the instructions read) before adding those drops to the test tube.  I don't know if API have resolved this problem or if it is simply systemic with the regent solution, but many have had high/inaccurate results when regent #2 was not shaken this long.
 
Nitrate is primarily connected to organics as the author points out.  More fish, more fish food, and more decaying plant and animal matter all contribute to increased organics.  High nitrate in well water is due to agricultural runoff, again organics.  Plant additives (= fertilizers) also add organics, as I will demonstrate momentarily.  Algae increasing can be due to higher nitrate because of the increase in organics feeding the algae (not the nitrate itself but the cause), and cyanobacteria is directly due to organics.  So keeping organics low clearly solves or helps to prevent many problems.
 
But sometimes it can be a mystery.  I have 8 tanks in my fish room, and in my 90g I have had slightly hazy water resulting from some sort of diatom/bacterial bloom for almost two years.  It comes and goes.  With the assistance of a couple of marine biologists and a microbiologist, organics have been identified as the cause, but it is still a complete mystery where these are coming from, or rather, why they are higher in this tank.  The fish load is far less than some of my other tanks, water changes have been 60-75% weekly (sometimes more often), and the filter is being cleaned regularly.  The filter is always remarkably "dirty," from the organic accumulation.  The floating Water Sprite develops thick accumulations of brown organics on the floating roots.  One thing I have worked out is that by eliminating all liquid plant fertilizers, things got a bit better; fertilizers are of course a part of organics.  Interestingly though, the plants in this tank have been out-growing the same species in any of the other tanks and you wouldn't believe by how much, notwithstanding the elimination of additives, which shows that they are using some of these organics.  I have even torn this tank down completely, with new sand, new wood and all new filter media.  Still the organics explode.  Nitrate in my tanks has always been in the zero to 5 ppm range.  In this "problem" tank, it runs around 10 ppm.  This is not particularly dangerous of course, but it does show the relationship of nitrates to organics.
 
As a microbiologist told me, even under what we view as "identical" conditions, each aquarium is a unique biological system and this becomes very evident when we see something like this.
 
Byron.

 

[julielynn47]

I have always shaken the #2 bottle for at least 30 seconds. But after reading on here about it settling I decided to shake the crap out of it this morning. And that might be why I got the higher reading.  I figure, all these years, I have just not been shaking it long or hard enough.
 
But  are these levels dangerous? Or are they pretty normal? That is what is bothering me now.  I don't think this high is a good thing, but maybe that is because I always thought the nitrates were at 0.  Now I am worried about it.
 
If it is just the test reading was not right, because I wasn't shaking it enough, then the fish have been doing okay with it.   But I am going to change the water and test it everyday for awhile and just see what happens with it.

 

[gmc1]

Some will disagree but in my opinion those levels are OK.

 

[Byron]

You indicate that your results with the long agitation of regent #2 are lower than without, but you don't give the number.  In post #1 it was 10-20 ppm.
 
Most reliable sources suggest 20 ppm as the upper limit, with the aim of keeping them as low as reasonably possible.  So if you are now seeing results less than 20 ppm, I wouldn't worry.  But, I would aim to keep them as low as you can, and if you find that say more plants, or less fish/food, or larger water changes achieve lower nitrate, it is not going to hurt at all to do them.
 
As it mentioned in the linked article, scientific studies have without question determined that nitrates are toxic to fish.  The toxicity relates to the species, the nitrate level, and the exposure period.  The higher the level, or the longer the exposure, or both, can cause difficulty, more for some species than for others.  So the best plan is to keep them as low as you can.
 
I discussed this at length with Neale Monks, and there are few sources in this hobby more knowledgeable or as highly respected as Dr. Monks.  He offered much the same as above.  When it came to the risks of nitrate toxicity, he was of the opinion that it weakens the fish much as any form of stress to start with, and this then leads to a weaker immune system, greater chance of disease, and a shorter lifespan.  Specific diseases linked to nitrate is not that well understood, but there is some evidence that a few may be.  We needn't go down that road here.
 
Byron.

 

[StevenF]

When we cycle a new tank bacteria colonize it and consume the ammonia and nitrite the fish produce.  The end produce from the bacteria is nitrate.  There are bacteria that consume nitrate but they require very low oxygen levels to live.  Those conditions will not exist in an aquarium.  So all aquariums  will have nitrate although in some cases at levels so low your typical test kit will not detect. Ammonia and nitrite are also present in all cycled tanks but typically at levels low enough that many test kits will show zero.  
 
There are typically only 2 ways to remove nitrate, cycle water out occupationally.  You are doing a 50% water change weekly which is correct.  Water changes also remove organics  The second common way to reduce it is to have health plant growth.  All plant and animal tissue contains nitrogen.  Fish will get is through the food.  But for the plants they must remove it from the water.   So if you have very good plant growth your test kit might only see a trace of nitrate.  Plants will also absorb other forms of nitrogen (ammonia, nitrite, and urea). The last way to remove nitrate is to use a special nitrogen absorbent in your filter canister.
 

 
 
Plant additives (= fertilizers) also add organics

While some fertilizers do contain organics many do not.  However most fertilizer contain nitrate because it is one of nutrients plants need most. Those fertilizers that contain Organics typically use it to keep iron in solution.  Iron is a trace nutrient that is not include in some fertilizers.Since iron is a trace nutrient only very low levels or organics are typically found in a bottle of plant fertilizer.  
 
since Nitrate is a very powerful acid it is typically not found in the by itself.  It always will react with something in the water creating a nitrate salt.  Common nitrate salts found in aquariums are potassium nitrate, sodium nitrate, calcium nitrate, and magnesium nitrate.  You might even find Ammonia Nitrate in aquarium water (ammonia is a base and will react with nitrate)  Since nitrate is a salt it will typically not evaporate from the aquarium like ammonia, nitrite and nitrogen can.  Nitrate will just build up in an aquarium until it is mechanically remove in  a water change or absorbed by a plant.
 

 
 So keeping organics low clearly solves or helps to prevent many problems.
 
But sometimes it can be a mystery.  I have 8 tanks in my fish room, and in my 90g I have had slightly hazy water resulting from some sort of diatom/bacterial bloom for almost two years.  It comes and goes. 

 Sudden water changes are frequently written off as a mystery simply because people do not do fully test the water for all nutrients in the water.  To do a full water chemistry workup you would need to test for about 50 different materials in the water.  Most people just don't have the time or money to do all of these tests.  so often the cause of a sudden algae issue never gets identified.  
 
Many people don't run water hardness GH or total Alkalinity tests on there water.  After all those levels are stable in the tap water and therefore they should stay stable in an aquarium.  This thinking is not correct because tap water is not chemically active.  An aquarium in comparison is always having chemicals removed and added.  So a aquarium is chemically very active place.  I have Seen GH changes dure to and or poor plant growth, and skipped water changes and when I started to get a high phosphate levels (caused by copper deficiency) under control my KH took a major drop due to plant growth suddenly accelerating.  I have also seen iodine levels suddenly climb a couple of times  and I think that was due to a drop in potassium levels ( I don't have potassium test kit but at the time i was not adding it to my RO water).
 
So your sudden change in nitrate may have had many causes.  Which one is hard to identify.  But since you are having a algae issue and i believe you have a planed tank.  You might be deficient in some nutrient and a reduction in plant growth could explain a sudden increase in nitrate.  You might want to try adding some Seachem Flourish Comprehensive fertilizer.  It is a complete fertilizer that has everything plants need.  Other causes of low plant growth is not enough light, or inconstant  aeration of the t water.  

 

[julielynn47]

I started using the Seachem Flourish Comprehensive a couple of weeks or so ago.   I also got the root tabs. Maybe I do just need more plants. I have quite a few, but probably nothing compared to most of you others

 

[Byron]

I started using the Seachem Flourish Comprehensive a couple of weeks or so ago.   I also got the root tabs. Maybe I do just need more plants. I have quite a few, but probably nothing compared to most of you others

 
I have been using this line for 7+ years and along the way discovered a few things.  The substrate tabs are excellent; Seachem claim these do not enter the water column except in the substrate and as taken up by the substrate-rooted plants, and to my knowledge this seems an accurate claim.  I mentioned that liquid ferts contribute to the organics (as Steven noted, it is not so much they add organics, but in my experience they certainly contribute to the presence of organics in my 90g), and the organically-related issue in my 90g has been considerably lessened by the total elimination of Flourish Comprehensive and Flourish Trace.  To compensate, and considering I have very soft water (basically zero GH) I have been adding the substrate tabs every two months instead of the 3-4 months.  There is absolutely no doubt but that the plants have benefited, in this and the other tanks.  I use these next to each large sword, my Cryptocoryne balansae, Aponogeton, and Red Tiger Lotus.  This has allowed me to significantly reduce the Flourish Comp and Trace in the other tanks too, and completely in this one.  It would seem logical that these additives were increasing the nutrients (which the plants do not need in such quantities), which in turn increased organics.
 
In one tank i experimented over one full year, and discovered that using Flourish Comprehensive, at two recommended doses per week, caused brush algae to appear and spread rapidly.  Reducing down to just one dose stopped the algae.  I did this twice over the year, same results, so there was a definite connection.
 
In the problem 90g, no liquid ferts other than one half-dose of iron and with the substrate tabs has not weakened the plants a jot.  In fact, they are thriving much better than in the other tanks (same species and lighting).  It is certainly possible to create a significant imbalance by excessive plant additives.  There is no doubt now in my mind that my initial approach of adding what I thought was needed was the wrong approach, and it is better to start from nothing and work up to what actually benefits without detriment.
 
Byron.

 

[AbbeysDad]

When you start a new tank setup (assuming the source water is nitrate free) there are no nitrates. Fish and fish waste generate toxic ammonia that is processed by nitrosomonas bacteria into toxic nitrites. Nitrites are processed by Nitrospira into less toxic nitrates*. This is what we refer to as the nitrogen cycle. If we were able to culture anaerobic bacterial, the nitrates would be oxidized into harmless nitrogen gas and the cycle would be complete. Now in a heavily planted tank, plants will use ammonia and nitrates so nitrate levels can remain quite low....much lower than a fish only tank. Nearly everyone knows that nitrates are typically removed via weekly partial water changes. What is often not understood is why, even with water changes, nitrates can increase over time. This of course is complicated by the level of collecting detritus in the substrate and filter. For discussion, lets say it's a fish only tank that generates 20ppm of nitrates a week. A 50% water change would reduce to 10ppm. By next week, nitrates are up to 30ppm. Another 50% water change takes them down to 15ppm. By the next week we're up to 35ppm....and so it goes. And if like me, you have nitrates in your source water....forget it!!!
In addition to water changes, you really need plants to keep nitrates at bay. Alternatively there are (as mentioned) resin products that go in the filter that will remove nitrates from the water column. API's Nitra-Zorb is one such product.
At the same time, we must not over stock or over feed. Substrate and filters must be routinely cleaned lest they become nitrate factories and source water for water changes must be nitrate free.
 
* There is an ongoing myth in the hobby (that many are convinced is true) that high nitrate levels are not harmful to fish. As Byron correctly points out this is completely untrue. And in nature, where these fish live naturally, nitrates are so low they cannot be measured. It's up to us as responsible fish keepers to keep nitrates as low as possible.
I have seen some proclaim that they never do water changes (only top offs for evaporation), have high nitrates, but their fish are just fine. They just don't get it!
 
-Michael

 

[julielynn47]

I was doing some researching on the Nita Zorb, and saw a post on using a Pothos plant as a way of removing nitrates also.  According to several places that I read they work really well. Just let the roots dangle in the tank and they are touted to suck up nitrate really well.   I might try that.  I would have to take the top off the hood I built for my tank. But I think it would not really be that noticeable since it is a flat surface anyway.  The sides would still be in place and not change the look much.  

 

[julielynn47]

Did a water change of 50% yesterday and the nitrate level was cut in half.  So I am going to do one every day of at least 25% and see if I can get it down further. After reading a lot online I find that high nitrates could be what caused the horrible algae problem. And can also be contributing to its return.   I have changed a lot of things, but just discovered the  nitates were high.  So hopefully if I get them down, and the phosphates are gone now, and I have new lights, hopefully this will take the tank back to where it used to be with no black algae

 

[Byron]

Did a water change of 50% yesterday and the nitrate level was cut in half.  So I am going to do one every day of at least 25% and see if I can get it down further. After reading a lot online I find that high nitrates could be what caused the horrible algae problem. And can also be contributing to its return.   I have changed a lot of things, but just discovered the  nitates were high.  So hopefully if I get them down, and the phosphates are gone now, and I have new lights, hopefully this will take the tank back to where it used to be with no black algae

 
Yes, this is likely.  Nitrates being high in the aquarium (as opposed to in the source water) indicates excess organics of some sort, and obviously this feeds algae.