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Question about Nitrates


Connor Elliott
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I put it against the white background like you are doing in your first picture.  I also shine a flashlight on it or put it under a desk lamp to get the best illumination that I can.  Of course, I suppose I could still be doing it wrong after all this time...

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Some say >20 is bad for sensitive critters like shrimp and some fish.  I have no way of knowing if that's right though.

 

Also to be pedantic (sorry) toxic is a matter of dose not substance.  80+ nitrate for example is probably toxic, 10 is probably not.

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53 minutes ago, CT_ said:

Some say >20 is bad for sensitive critters like shrimp and some fish.  I have no way of knowing if that's right though.

Also to be pedantic (sorry) toxic is a matter of dose not substance.  80+ nitrate for example is probably toxic, 10 is probably not.

There are plenty of scientific studies on nitrate toxicity. The 96-hr LC50s are in the 4,000-8,000 ppm range. Ten percent of that is considered OK for chronic exposure. And indeed salmon have been kept at 443 ppm for 8 months with no ill effects (they even performed blood work on them).

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Ok yeah then lets say 8000 is surly toxic. 

 

Someone posted a study here showing 40 significantly hindered growth for something common (I forget which fish).  All I know is what people have said and what literature I've read.  I'm sure it depends on species too.

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I decided to do more reading and it looks like young fish and inverts are especially sensitive.  Some have an LC50 10's of nitrate and low percentage LC in the 1's.  I guess it's all very species dependent.

 

This has some good tables but its mostly for juveniles and younger.  https://www.waterboards.ca.gov/water_issues/programs/tmdl/records/region_2/2008/ref2426.pdf

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I saw a study of rainbow trout kept at 10 ppm nitrate and another batch kept at 100 ppm nitrate and there was no difference in health, I am neutral on the issue, my boss never changes water in his tank (yikes!) and I tested his nitrates one time and they were like 300 or something crazy, all his fish were fine he never has any disease or anything and they don't show signs of stress, he also adds new fish without an issue, they don't go into shock. 

That being said, I have plenty of friends who swear that over 40 nitrate causes damage, so I just do water changes at 40 ppm nitrate or if my PH starts to drop (I have really hard water, but lower in KH) Usually do a change every weekend or every two weeks because I enjoy taking care of the tanks anyway. 

Nitrate is probably not the only thing that can become an issue in old tank syndrome, so I do still recommend doing water changes unless your an expert that knows how iron levels or phosphate levels or whatever else is in the water will impact your tank. 

 

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3 hours ago, CT_ said:

Ok yeah then lets say 8000 is surly toxic. 

 

Someone posted a study here showing 40 significantly hindered growth for something common (I forget which fish).  All I know is what people have said and what literature I've read.  I'm sure it depends on species too.

There just isn't scientific evidence to support the hobby's 40 ppm recommendation.

3 hours ago, CT_ said:

I decided to do more reading and it looks like young fish and inverts are especially sensitive.  Some have an LC50 10's of nitrate and low percentage LC in the 1's.  I guess it's all very species dependent.

This has some good tables but its mostly for juveniles and younger.  https://www.waterboards.ca.gov/water_issues/programs/tmdl/records/region_2/2008/ref2426.pdf

Amphibians and some invertebrates seem to be more sensitive. There's a dramatic difference based on life stage though. Eggs and larvae/fry are the most sensitive. The papers discussing where to set discharge limits have to consider the most vulnerable life stage and species since they have an entire food chain to protect. Young life stages don't produce enough methemoglobin reductase that reverses the effects of nitrite in the blood (fish swallow nitrate-laden water which is then converted to nitrate in the digestive tract).

That Camargo paper is usually the first that Google spits out. It relies on the discredited Kincheloe 1979 study for some of its lowest numbers. Later studies attempted to replicate the results but the numbers they got were several magnitudes larger.

https://pubmed.ncbi.nlm.nih.gov/16916038/

662850069_Kincheloediscredited1.png.f3b473e39191a119e7fe98b3511f6383.png1821992020_Kincheloediscredited2.png.1b43debcf0ae7eef36fa802ee64f76e2.png

 

3 hours ago, darkG said:

Here are some findings:

imagehttps://doi.org/10.1002/etc.4701

This seems like a good time to point out that nitrate-nitrogen is nitrate * 4.43 so if the EC20/LC20 for a particular species is 1,000 mg/L nitrate-N it's 4,430 mg/L nitrate. EC20/LC20 should be lower than LC50 so the acute toxicity levels for fish are in the >4,000 mg/L nitrate range. No normal aquarium is going to subject fish to a chronic level of nitrate 10% of that. And you can see why fussing about 20 vs. 40 ppm isn't important.

2 hours ago, Daniel said:

I am pretty full of myself most days, but I would think twice before I got into a discussion with @Coronal Mass Ejection Carl about nitrates. I think he buys them by the barrel load.🙂

I've spent more time reading nitrate toxicity papers than studying for graduate level courses. It's become a hobby now and every few weeks I search for any new papers on nitrate or oxygenation.

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1 minute ago, GardenStateGoldfish said:

I saw a study of rainbow trout kept at 10 ppm nitrate and another batch kept at 100 ppm nitrate and there was no difference in health, I am neutral on the issue, my boss never changes water in his tank (yikes!) and I tested his nitrates one time and they were like 300 or something crazy, all his fish were fine he never has any disease or anything and they don't show signs of stress, he also adds new fish without an issue, they don't go into shock. 

That being said, I have plenty of friends who swear that over 40 nitrate causes damage, so I just do water changes at 40 ppm nitrate or if my PH starts to drop (I have really hard water, but lower in KH) Usually do a change every weekend or every two weeks because I enjoy taking care of the tanks anyway. 

Nitrate is probably not the only thing that can become an issue in old tank syndrome, so I do still recommend doing water changes unless your an expert that knows how iron levels or phosphate levels or whatever else is in the water will impact your tank.

Yeah, it's actually 44.3 vs. 443 mg/L nitrate once you convert the units. For 8 months. I don't think anyone is hitting 400+ for months on end.

I'm now actually more concerned about dissolved organic carbon:

https://www.sciencedirect.com/science/article/abs/pii/0144860988900064

960420575_2020-08-1218_10_33-hirayama1988.pdf-AdobeAcrobatProDC.png.0181c9f3b0c1b1c60bde39aedb7620bd.png

It takes around 1,000 mg/L nitrate-nitrogen to inhibit growth in tilapia. Here, levels of DOC 125 times less were doing it. Not to mention there's a strong correlation between organic waste and disease but not with nitrate.

The control group in this study experienced spontaneous denitrification hence the low nitrate value.

What I'm afraid of is that organic waste trapped in filters/substrate continuously break down and release DOC and frequent filter cleanings, not water changes, are needed.

That means that people doing water changes every week and cleaning filters twice a year have it backwards.

It requires several thousand dollars of equipment to test DOC so it's going to be awhile before better technology lowers prices.

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Now back to the original question. ☺

I thought I saw somewhere that API says to hold a finger between the tube and white part of the color chart to get an accurate reading so that's how I've been doing it. 

I have also compared the results to a salifert Nitrate test kit, which there is no controversy on how to read it, and they are close.

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I don't think we can trust studies done on farmed fish because they'll be in the freezer or on the table long before they reach their full life span. It's long been held that high nitrates lowers fish immune systems and shortens life spans in aquarium fish.

Now most hobbyists may think their fish live average or long life spans, not even realizing that well kept tropical fish could live 15-20 years...but most surely don't!

With over 50+ years in the hobby, I've found that the very highest water quality yields the fastest growing fry, and the largest, healthiest fish with the best vigor and color.

The greatest success in the hobby comes with the highest possible water quality. 🙂

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7 hours ago, MJV Aquatics said:

I don't think we can trust studies done on farmed fish because they'll be in the freezer or on the table long before they reach their full life span.

A lot of those studies are for establishing discharge limits in natural waters. Not to mention there are a few on fathead minnows, guppies, and gamefish.

7 hours ago, MJV Aquatics said:

It's long been held that high nitrates lowers fish immune systems and shortens life spans in aquarium fish.

There's no scientific evidence of this though. And age in fish isn't just related to years but growth rate and size. A fish that's grown rapidly to market size is chronologically young but biologically older as it's at the point where feed conversion ratio drops and it's no longer economical to keep growing them. Anything that doesn't manifest in those eight months probably isn't ever going to manifest.

7 hours ago, MJV Aquatics said:

With over 50+ years in the hobby, I've found that the very highest water quality yields the fastest growing fry, and the largest, healthiest fish with the best vigor and color.

Growing fish fast and big shortens their chronological lifespans so I don't know if this is really a good measure of success. But it is exactly what fish farms try to do...

7 hours ago, MJV Aquatics said:

The greatest success in the hobby comes with the highest possible water quality. 🙂

What is water quality? Why are we focused on nitrate which is only one of three nutrient cycles? Cleaning filters might actually be more important than changing water.

A lot of people do leave the hobby and I think the peer pressure over nitrates and water changes is part of it.

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Nitrate bonds with Hemoglobin to create Methoglobin which can no longer carry oxygen.   This causes low oxygen concentrations in the fishes blood,(Human Blood, Livestock Blood, ect) requiring the fish to inhale more oxygen.

in the study below, it found at around 100 ppm nitrate, oxygen was consumed at 3 times the rate with water at 0 nitrates.

https://academic.oup.com/conphys/article/8/1/coz092/5658492

While not completely analogous, it seems like climbing mount Everest, where the higher one goes/ the higher the nitrates go, the less oxygen is able to be used.  

Having to take a breath more often than you are used to 24/7/365, the stress of that can't be good.
 

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2 hours ago, Coronal Mass Ejection Carl said:

Anything that doesn't manifest in those eight months probably isn't ever going to manifest.

I disagree. Fish may tolerate poor water quality for months, but it may shorten their lives by years. Studies on farmed fish can never reveal that.

2 hours ago, Coronal Mass Ejection Carl said:

Growing fish fast and big shortens their chronological lifespans so I don't know if this is really a good measure of success.

Not when we're talking of higher water quality do to the frequency of partial water changes.

2 hours ago, Coronal Mass Ejection Carl said:

A lot of people do leave the hobby and I think the peer pressure over nitrates and water changes is part of it.

I believe that a lot of people leave the hobby because the aquarium was an impulse buy, over time they lost interest, didn't take care of it and fish died. It most likely has little to do with pressures over nitrates and water changes.

Too many 'hobbyists' seem to not want to do partial water changes so they wish to believe that expert advice about low nitrates just isn't real.

My experience over 5+ decades is that fish do best in high(er) quality water, with plants, advanced bio-filtration, and routine partial water changes. An hour a week to service a tank (filter/water change) seems like a small price to pay. 🙂

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12 minutes ago, MJV Aquatics said:

I disagree. Fish may tolerate poor water quality for months, but it may shorten their lives by years. Studies on farmed fish can never reveal that.

A lot of those studies are for establishing discharge limits in natural waters. Not to mention there are a few on fathead minnows, guppies, and gamefish.

Age in fish isn't just related to years but growth rate and size. A fish that's grown rapidly to market size is chronologically young but biologically older as it's at the point where feed conversion ratio drops and it's no longer economical to keep growing them. Anything that doesn't manifest in those eight months probably isn't ever going to manifest.

Growing fish fast and big shortens their chronological lifespans so I don't know if this is really a good measure of success. What fish farms and hobbyists do isn't any different.

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15 minutes ago, MJV Aquatics said:

Too many 'hobbyists' seem to not want to do partial water changes so they wish to believe that expert advice about low nitrates just isn't real.

The vet at UC Davis told me that <150 ppm was fine but what do they know they only take care of the exhibits in public aquariums and aren't "experts."

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