The is another potential source for nitrate in the water, and that is the plumbing system in one's home. For those who have their water supplied by municipal systems may not be aware that the process of quality control by a municipal system ends at the property line. What is happening in the pipes from the property line on into the home are under the control of the owner.
It is common for nitrifying bacteria to colonize in such home systems. For many people there are sinks , toilets etcs which are not being used all that frequently. When this is the case they provide a nice safe place for the bacteria. All that is required for this to happen is that there is some ammonia in the water.
The advent of chloramine use in municipal water systems has greatly impacted what may happen in private pipes. The breakdown of residual chloramine after the water exits the municipal system provides the needed ammonia to foster nitrifying bacterial colonies in home plumbing. And as we all know the end of the nitrification process in aerobic systems is nitrate.
I first became aware of this in reading research papers. I stumbled across a doctoral thesis which investigated this. It eventually morphed into a published study.
Here is one example:
Bradley, T.C.; Haas, C.N.; Sales, C.M. Nitrification in Premise Plumbing: A Review.
Water 2020,
12, 830.
https://doi.org/10.3390/w12030830
Abstract
Nitrification is a major issue that utilities must address if they utilize chloramines as a secondary disinfectant. Nitrification is the oxidation of free ammonia to nitrite which is then further oxidized to nitrate. Free ammonia is found in drinking water systems as a result of overfeeding at the water treatment plant (WTP) or as a result of the decomposition of monochloramine. Premise plumbing systems (i.e., the plumbing systems within buildings and homes) are characterized by irregular usage patterns, high water age, high temperature, and high surface-to-volume ratios. These characteristics create ideal conditions for increased chloramine decay, bacterial growth, and nitrification. This review discusses factors within premise plumbing that are likely to influence nitrification, and vice versa. Factors influencing, or influenced by, nitrification include the rate at which chloramine residual decays, microbial regrowth, corrosion of pipe materials, and water conservation practices. From a regulatory standpoint, the greatest impact of nitrification within premise plumbing is likely to be a result of increased lead levels during Lead and Copper Rule (LCR) sampling. Other drinking water regulations related to nitrifying parameters are monitored in a manner to reduce premise plumbing impacts. One way to potentially control nitrification in premise plumbing systems is through the development of building management plans.
(full paper
https://www.mdpi.com/2073-4441/12/3/830)
When I did a search for "nitrate in home plumbing" on Google Scholar I got back "about 15,900 results."
Of course for those of us who have private wells this is not as much of a concern. What would be is what
gwand posted above. But I would bet that the majority of folks who have aquariums also have a municipal water supply.
I have never really worried about nitrate in most of my tanks. The reason for this is my dedication to weekly water changes of 50-60%. The few nitrate tests I did early on never showed worrisome levels. And then I began doing live plants. These use nitrate in the absence of ammonium (yes plants use NH4 and the bacteria much prefer to use NH3 but can use NH4 less efficiently).
The one place I had to be aware of nitrate levels was when I began working with zebra plecos. Zebra fry do not react well to nitrate. Since I prefer to leave fry in the breeder tanks for as long as possible, I did occasional test for nitrate. I discovered my water change routine gave me decent control over nitrate since it was not coming in via my tap water.
But, I live i an area with little farming. In fact, a great deal of the water supplies to NYC comes from reservoirs within not many miles from me. I regularly drive past these in my day to day travels.
However, the potential danger of excess nitrate in our tanks comes from multiple sources. If from nowhere else, it comes from then itrogen cycle in our tanks. However, some of us have set-ups which foster denitrification. For me that is my Hamburg Matten filters. Others may have planted tanks or deeper substrate which can host facultative bacteria. These can process oxygen which it is available, but when it is not, they can switch over to using nitrate.
Most of us have the facultative bacteria in our tanks but what we may not have is anaerobic areas where they will switch to using nitrate. The problem is that in the substrate there is minimal circulation. So even if we have the right bacteria getting water to circulate in a few inch deep substrate is not so easy. it is why the ammonia and nitrite oxidizers only function in the top portion of substrate. By amn inch depth there is little to no oxygen.
If we look at nature itself, the nitrogen cycle naturally results in the final step which is denitrification which returns nitrogen to the atmosphere as N2. For the most part this is because of bacteria which work in anaerobic conditions.
However, in tanks with live plants rooted in the substrate, the right plants actually work to transport oxygen down to their roots and release it into the anaerobic areas. This foster nitrification.The most interesting thong about this is it also fosters area of denitrification above and below the area where the bacteria have colonized due to the availability of oxygen which is essential for them for function.
If you are curious about this hare is a link which will bring up a number of papers on this:
https://scholar.google.com/scholar?...phyte+Lobelia+dortmanna+L.+&hl=en&as_sdt=0,33
The above link was generated by calling up the first study you will see and then clicking on "related articles." Here is the abstract for that first paper:
Petersen, N.R. and Jensen, K., 1997. Nitrification and denitrification in the rhizosphere of the aquatic macrophyte Lobelia dortmanna L.
Limnology and Oceanography,
42(3), pp.529-537.
Abstract
Nitrogen and O2 transformations were studied in sediments covered by
Lobelia dortmanna L.; a combination of 15N isotope pairing and microsensor (O2, NO3−, and NH4+) techniques were used. Transformation rates and microprofiles were compared with data obtained in bare sediments. The two types of sediment were incubated in doublecompartment chambers connected to a continuous flow-through system.
The presence of
L. dortmanna profoundly influenced both the nitrification-denitrification activity and porewater profiles of O2, NO3−, and NH4+ within the sediment. The rate of coupled nitrification-denitrification was greater than sixfold higher in
L. dortmnanna-vegetated sediment than in bare sediment throughout the light–dark cycle. Illumination of the
Lobelia sediment reduced denitrification activity by ∼30%. In contrast, this process was unaffected by light–dark shifts in the bare sediment. Oxygen microprofiles showed that O2 was released from the
L. dortmanna roots to the surrounding sediment both during illumination and in darkness. This release of O2 expanded the oxic sediment volume and stimulated nitrification, shown by the high concentrations of NO3− (∼30 µM) that accumulated within the rhizosphere. Both 15N2 isotope and microsensor data showed that the root-associated nitrification site was surrounded by two sites of denitrification above and below, and this led to a more efficient coupling between nitrification and denitrification in the
Lobelia sediment than in the bare sediment.
