Hi All,
Tanks looks kinda healthy with amonia and nitrites at near zero but my nitrates were at 80ppm before water change and then 40ppm after. Is that still too high? What should it be do you think?
Many Thanks
James
Abstract: Cyprinus carpio, common carp was exposed to subleathel concentration (12 ppm) of nitrate (KNO3) under acute and chronic static bioassay conditions. The resultant histopathological changes in the liver were recorded by light microscopy. LC50 values of nitrate, according to Reed-Muench method, were 995 ppm for 48 hrs and 865 ppm for 96 hrs. For the acute tests, the fish were exposed to 12 ppm of nitrate for 1,2 and 4 days. For chronic tests, the fish were treated with 12 ppm of nitrate for 8, 16 and 32 days. Control fish were maintained in parallel with the experimental groups. Increase in Bowman’s space, degeneration of glomeruli, shrinkage of proximal tubule cells with pycnotic nuclei, increased tubular lumen and increased in intratubular hematopoietic tissue were the most significant changes observed in fish kidney after nitrate exposure. The effects were time dependent being more pronounced in acute treatments. The present investigation illustrates that presence of high concentration of nitrate in water are stressful to fishes.
GENERAL OBSERVATIONS AND BEHAVIORAL RESPONSE
Acute and chronic treatment of fish with 12 ppm nitrate revealed substantial changes in fish behavior. These involved abrupt and sluggish swimming movements in various directions indicating an avoidance response. Occasional jumping and hitting the walls of aquaria were also noted.
As far as general condition of fish is concerned, rapid scale loss, especially from head region, was observed in acute treatment groups. These changes were more pronounced during the initial hours of exposure of fish to nitrate. Surprisingly, defecation by almost all challenged fish was recorded with in 30 minutes of exposure to nitrate Excessive secretion of mucous by treated fish was also observed which was particularly marked in the fish exposed to acute nitrate treatment where aquarium water became cloudy.
MATC = maximum acceptable toxicant concentrationFinally, the U.S. EPA's recommendation of a maximum of 90 mg/L NO3-N for the protection of warmwater fishes would protect Topeka shiners but not fathead minnows. For Topeka shiners, the MATC from the 30-d juvenile growth test was 360 mg/L NO3-N, but for fathead minnows, the MATC was 84 mg/L. More field sampling may be needed to determine if levels comply with criteria, especially in Topeka shiner critical habitat.
I keep mine at 10-20ppm.
Michel.
Generally the lethal nitrate dose for fish is way over 1600ppm, so you have way to go yet.
As Darrel says inorganic sourced nitrate levels aren't nearly as toxic as organic sourced nitrates as organic sourced come with a lot of "extra baggage", nitrite, ammonia and other oxygen depleting organics, that all together cause toxicity issues.Where on earth do you get this figure from? everything I've read regarding general tolerance levels of nitrates for fish states 30ppm - 40ppm and for Goldfish, Koi etc as being even lower - at 20ppm - as safe levels. There are fish that are exceptions with tolerances much higher, but these aren't 'general'
1600ppm seems an awfully wide error margin.
Exactly, the potassium nitrate can safely reach 1400ppm, but organic nitrates at those levels will almost certainly be fatal to fish in general.As Darrel says inorganic sourced nitrate levels aren't nearly as toxic as organic sourced nitrates as organic sourced come with a lot of "extra baggage", nitrite, ammonia and other oxygen depleting organics, that all together cause toxicity issues.
A quick scan of potassium nitrate MSDS (material data sheet) reveals an aquatic LD (lethal dose to kill 50%) of 1400ppm.
So if nitrate source is plant food, you can run higher ppm without issues.
A quick scan of potassium nitrate MSDS (material data sheet) reveals an aquatic LD (lethal dose to kill 50%) of 1400ppm.
I'm firmly in the "low nitrate" camp, but there is some research that quotes levels in the hundreds of ppm NO3 as safe. This one is from the <"Zebrafish" journal>.Both studies use inorganic nitrate (salts)
from "Acute and Chronic Toxicity of Nitrate to Early Life Stages of Zebrafish—Setting Nitrate Safety Levels for Zebrafish Rearing".Based on NOEC (no observed effect concentration) values, safety levels should be set at 1450, 1855, and 1075 mg/L NO3−-N to prevent acute lethal effects in embryos, newly-hatched larvae, and swim-up larvae, respectively. In the chronic bioassay, larvae were exposed to nitrate concentrations of 50, 100, 200, and 400 mg/L NO3−-N during the entire larval period (23 days). No negative effects were observed either on larval performance or condition at concentrations up to 200 mg/L NO3−-N. However, at 400 mg/L NO3−-N, survival drastically decreased and fish showed reduced growth and evidence of morphological abnormalities. Accordingly, a safety level of 200 mg/L NO3−-N is recommended during the larval rearing of zebrafish to prevent negative impacts on juvenile production.
Abstract
Published data on nitrate (<img height="17" border="0" style="vertical-align:bottom" width="36" alt="View the MathML source" title="View the MathML source" src="http://origin-ars.els-cdn.com/content/image/1-s2.0-S0045653504009993-si1.gif">NO3-) toxicity to freshwater and marine animals are reviewed. New data on nitrate toxicity to the freshwater invertebrates Eulimnogammarus toletanus, Echinogammarus echinosetosus and Hydropsyche exocellata are also presented. The main toxic action of nitrate is due to the conversion of oxygen-carrying pigments to forms that are incapable of carrying oxygen. Nitrate toxicity to aquatic animals increases with increasing nitrate concentrations and exposure times. In contrast, nitrate toxicity may decrease with increasing body size, water salinity, and environmental adaptation. Freshwater animals appear to be more sensitive to nitrate than marine animals. A nitrate concentration of 10 mg NO3-N/l (USA federal maximum level for drinking water) can adversely affect, at least during long-term exposures, freshwater invertebrates (E. toletanus, E. echinosetosus, Cheumatopsyche pettiti, Hydropsyche occidentalis), fishes (Oncorhynchus mykiss, Oncorhynchus tshawytscha, Salmo clarki), and amphibians (Pseudacris triseriata, Rana pipiens, Rana temporaria, Bufo bufo). Safe levels below this nitrate concentration are recommended to protect sensitive freshwater animals from nitrate pollution. Furthermore, a maximum level of 2 mg NO3-N/l would be appropriate for protecting the most sensitive freshwater species. In the case of marine animals, a maximum level of 20 mg NO3-N/l may in general be acceptable. However, early developmental stages of some marine invertebrates, that are well adapted to low nitrate concentrations, may be so susceptible to nitrate as sensitive freshwater invertebrates.
Abstract
Although nitrate is a ubiquitous component of aquatic environments, and has become a global pollutant in a variety of aquatic systems, it has only recently begun to receive attention for its ability to alter endocrine function. Aquaculture environments with limited water exchange often contain nitrate concentrations far in excess of natural environments, yet nitrate's impact on the reproductive health and endocrine function of commercially important species residing in these environments has not been investigated. Two experiments were conducted evaluating the effects of elevated nitrate on cultured Siberian sturgeon (Acipenser baeri). The first experiment compared the effects of a 30 day exposure to 11.5 ± 0.36 and 57 ± 2.18 mg/L nitrate-N concentrations on plasma cortisol (F), glucose, 17β-estradiol (E2), testosterone (T) and 11-ketotestosterone (11-KT) concentrations. The second experiment was similar to the first but evaluated concentrations of 1.5 ± 0.057 and 57 ± 1.52 mg/L nitrate-N. In both experiments, after 30 days of exposure to a given nitrate concentration, blood samples were obtained at time 0, and a portion of those fish were then placed under confinement stress for a period of 6 h to evaluate whether nitrate affects the associated stress response. The fish were bled at 1 h and 6 h during the confinement period. Results revealed that 57 mg/L nitrate-N exposure was associated with an increase in plasma T, 11-KT and E2 concentrations at time 0, but did not alter the associated stress response defined by elevated plasma cortisol concentrations. An additional measure of the stress response, plasma glucose concentration, however, was altered by nitrate exposure during the 6 h period of confinement stress in Experiment 1, but was not in Experiment 2. These findings demonstrate that nitrate has the potential to disrupt endocrine function and possibly secondary stress responses in cultured Siberian sturgeon.
They certainly do. A lot of the problem goes back to accurate measurement, particularly at low NO3- levels in water with an unknown level of other anions (often Cl- or SO2--).groups supporting aquaculture where high nitrate buildup occurs, tend to find fishes that show limited impact ... or perhaps much depends on how impact is being measured/determined