NO3 vs. Fish

[k-maub]

While I have gotten away from the EI method (adding less ferts (usually just K and micro), doing fewer water changes), I am seriously considering getting strict about it again. Plants are doing great, but I am not terribly happy with the overall health of my fish. I think if I follow EI more strictly, I will see lower overall TDS levels and hopefully as a result, better fish health.

I'm having trouble with the fact that it has been argued by Tom and others that fish are not as susceptible to high nitrates as is commonly believed. I agreed to a certain extent. However, he has also written (sorry I don't have a link), that generally, more water changes are better for fish health. Can someone help me reconcile the two stances? What exactly about frequent water changes is so great for fish? If it is unrelated to nitrate levels, what dangers are there to keeping a low-tech, few water-changes planted tank?

Thanks.

 

[Tom Barr]

Water changes= more CO2, more removal of waste or any excess.

In other words, more stability.

Since you do more water changes, you have closer ranges in your estimation.

If you did a 50% water 3x a week and dosed thereafter, you'd have about 5-15ppm range of NO3 at most any light level.

You'd also have excellent growth, algae spore removal, clean clean tank, you'd fluff the plants good, knocking off algae, you'd dose plenty of good ferts each time and would have massive pearling 3-4 days of the week.

You do not have to be strict, that was never the goal.
You can whip a tank into shape, then back off some.

So doing 2-3x a week to get things in shape is not a bad idea, then relax to 1x a week.

Likewise, you do not need to do 50% only, you can do 30% 2x a week, or 70% once a week etc.

Regards,
Tom Barr

 

[k-maub]

I completely understand what you're saying in regards to plant health.

However, please help me reconcile the fish side of water changes. You have asserted before that water changes are good for fish health (forgive me for not being able to specifically cite this).

Why do you make this statement? It is as simple as avoiding toxicity of NO3? Another compound that may be more problematic for fish health?

Or is there something aside from avoiding fertilizer toxicity (high TDS) such that the fish favor water changes?

Is this anecdotal evidence for improved fish health, or is there a concensus as to the source of the benefit?

Thanks!

 

[Tom Barr]

Fish waste(urea/NH4 etc) and KNO3 are two very different things, however, many seem complacent with lumping them together.

Ideally you want some fish waste and the rest from KNO3 in higher light tanks.
I'd say removal of NH4 based nutrients vs NO3 are much more an issue.

If you have a high growth planted tank, adding NH4 can be done, like wise adding a fair amount if you do water changes daily or more frequently than weekly will also work at higher levels.

Why not look at it from a fish perspective then?
What's more toxic per Nitrogen atom?
NH4 or NO3?

How about for algae?

Removal of NO3 is not the goal, merely preventing the NO3 from getting way too high, say over 30-40ppm is all the water changes do for NO3.

NH4, as low as you can get it.
Water changes also add a lot of CO2 and O2 to the tank.
This is good for the plants and bacteria.
It fluffs the plants and gets any left over organic waste out.


Regards,
Tom Barr

 

[Carissa]

I find that a happy medium works the best for me. I've done the 50% weekly water changes, and I've also left tanks for a month with no water changes. My fish and plants seem to do best with weekly 25-30% water changes. The 50% was a bit drastic, I used to lose a fish or two after the water change. My particular water is 0 KH and GH, so I had to reconstitute the GH every single time; plus the sand in my tank leaches KH and my tap water has none; I was probably just changing parameters too suddenly with the 50% water changes. But leave a tank for two weeks or more with no water changes, and I see a definite decline in fish and plant health. As to why this is, I think Tom is totally right, it removes excessive organic waste that causes problems if it builds up too much. I don't add very many fertilizers to my tank that would require me to do the weekly changes for that reason, but just the same, everyone is happier when the water changes are done regularly, fertilizing or not.

 

[k-maub]

So let me try to summarize after I ask a question. By organic waste, are we referring to NH4 or are there other compounds that I'm probably not aware of that build up? If that's the case, and the plants don't eat them, how big a problem does it become in a low-tech, infrequent water change tank?

So basically, per some of the papers Tom has listed in the past, NO3 at moderate levels (~50 ppm and below?) do not seem to affect fish health. So the arguement that is is poisonous and should always be kept as low as possible is a little bunk (especially when you are trying to keep plants).

This opens the door for methods like EI where "over"-dosing can be condoned to the extent that it improves plant health without negatively affecting fish health, as long as water changes are performed to prevent build up.

My confusion originated when I got to thinking that nitrates in the 100 ppm - 200 ppm range were also relatively safe for fish. While many of my fish tolerated those conditions, I was unhappy with the number of fish that suffered poor health. So it seems that indeed, those levels are too high, and for most fish there is a lower upper-limit. Would we say 40 ppm? 50 ppm?

Thanks for everyone's input.

 

[Tom Barr]

Organic waste are the sum total of the fish feces, urine, plant decompsotion from dead leaves and leakage, bacteria waste, rotting driftwood, soil, peat etc, anything that can be broken down.

It's a large group of chemical compounds.

Happy medium is a good concept, far too many take things too far one way or the other. You have a set of trade offs, you can dose less if you use less light etc, or have a higher fish load, but too far one way or the other causes issues.

You can also do more water changes or % or both, that will give you more close tolerances to any potential build up.

I need to add irrigation water to the yard other wise the landlord whines.
So I use tank water. I rarely use tap.

So it's not wastewater.

Other folks with lower fish loads, lower light etc, can easilyget away with fewer water changes, however if you want a really nice looking tank, and keep it really looking good, weekly water changes are wise.

Both myself and ADA came to this conclusion (and virtually every good scaper) independently of eachother.

When folks suggest low as possible, that's not bad unless you are talking about plants, obviously N is a fertilizer and we must add it for growth of the plants.

So there's really an issue of what is the risk at a certain ppm of a chemical.
That's where bones heads get into the fray and claim any amount is deadly, or bad etc.

Plants need copper, so do shrimp etc, us and fish for that matter, but not too much, not too little.
Like anything.

It's about the "dose" not the mere presence of a compound. You can never get away with entire removal etc. the real question is how much is truthfully "bad" and how much leeway do we have.

That is useful information, the other claims and stupid comments?
Nothing but fear based mongering.




Regards,
Tom Barr

 

[Carissa]

Interesting article here...

New research highlights nitrate toxicity | Practical Fishkeeping magazine

suggesting that nitrate toxicity can be cumulative over time and dependent on a variety of things such as the type of organism and the size. I would like to see the paper the article is based on but I'm not sure how to get it.

 

[VaughnH]

A lot of people have been dosing nitrates at the EI levels for 4 years now, and I don't recall seeing a mass of reports about fish problems that resulted from that. There have been some reports of shrimp problems that might be nitrate related, but not fish problems. And, this is people dosing at 20 ppm or more of NO3, not the 3 ppm mentioned in that article. When theory conflicts with data, the theory is usually the loser.

 

[Tom Barr]

Errr, 20 ppm of N-NO3 is not 6ppm............that's 20 * 4.4= 88 ppm of NO3, pretty high.............

Salmon and trout are extremely sensitive compared to virtually all other species of fish.

Chronic vs acute toxicity is an issue, however, as the study states: it is species dependent. You can talk about trout, etc, you cannot talk about warm water fish however.



http://www.aseanenvironment.info/Abstract/41013039.pdf

I think if you read the sections of NH3/NO2 and NO3, you will see that this is not very specific nor telling for aquariums, it is, rather, geared towards environmental science and policy making.

Big difference.

I can easily find an article that claims they found 2 ppm of NO3 killed a species of shrimp.

Then I can speculate that all shrimp is aquarium are the same and will act and behave the same to this same ppm of NO3, and suggest that "just to be on the safe side" as so many a scare mongers' before have done.........say everyone should do this.

The article is good etc, and does an ample job.
However, the researchers also make VERY CLEAR the differences in toxicity and what they know vs they do not know.

This article does not tell you much.
How you measure NO3 toxicity to live living critters is alos an issue with sub lethal effects, at the Aquatic toxicology lab at UC Davis Ron has some cool things the measure just these types of questions in terms of in situ metabolism.

But like any good researcher, he's keen not to jump to conclusions and make scare monger claims.

Read it and see if you can find one reference to any warm water tropical fish.
There aren't any.

Regards,
Tom Barr

 

[Tom Barr]

Interesting article here...

New research highlights nitrate toxicity | Practical Fishkeeping magazine

suggesting that nitrate toxicity can be cumulative over time and dependent on a variety of things such as the type of organism and the size. I would like to see the paper the article is based on but I'm not sure how to get it.

I got the article and read it.

There's nothing new here as far as shrimp or fish from warm tropical water.
Additionally, the article is particularly damning when respect to toxicity and the claims proposed in the PFK article.

For the guppy, one of the few warm water species discussed, the toxicity levels are for only actute levels and for no more than 96 hours.

The drop off rate for LD50 is very low over time.

Here's the data adapted from Rubin and Elmaraghy, 1977(hardly "new") for the table:

Poecilia reticulatus Fry Freshwater 267 (24 h LC50)b Rubin and Elmaraghy (1977)
Fry Freshwater 219 (48 h LC50)b Rubin and Elmaraghy (1977)
Fry Freshwater 199 (72 h LC50)b Rubin and Elmaraghy (1977)
Fry Freshwater 191 (96 h LC50)b Rubin and Elmaraghy, 1977 A.J. Rubin and G.A. Elmaraghy, Studies on the toxicity of ammonia, nitrate and their mixture to guppy fry, Water Res. 11 (1977), pp. 927–935.

They used Sodium nitrate BTW.
Also, other cations also can play a major role in the toxicity of NO3 and reduce it greatly.

The NO3 is also NO3-N, so multiply by 4.4 and you get 800ppm ranges or more of NO3.

This is well over 10X EI levels if you never had any NO3 uptake at all.
But typical ranges for EI are more in the 10-30ppm ranges.
Still, this is a long long way off from the supposed inferences claimed in the article which is appears was not read in it's entirety and critically read.

It does not say anything about the fish or critters we keep and as you can read from the various tables, the range is massive for trout fry vs guppies vs other critters.

They focused specifically on naturally loaded systems and the inverts that where/are present in Spain.

Not in your tank.
The review is good etc, the interpretation and application to our hobby is not however.


Regards,
Tom Barr

 

[k-maub]

So, not surprisingly, what you're saying is that different species have different sensitivities to different fertilizers. For instance, cold water fish seem especially sensitive to nitrates.

For our tropical, freshwater tanks, can somebody suggest some over-arching guidelines? Maybe not perfect, maybe there are species that are especially sensitive, but what might be max safe ppm levels (nitrate/phosphate/trace) for the average aquarist keeping the most common fish/shrimp/snails?

Tom, it sounds like you have done some of these tests and have some data. Otherwise, anecdotal evidence from others could be used to determine at what levels of various fertilizers they have had with healthy fish.

Also, do we need to consider cumulative effects of multiple ions? Would TDS be an important number to track, or do we need to only track individual ingredients?

Thanks again!

 

[Tom Barr]

So, not surprisingly, what you're saying is that different species have different sensitivities to different fertilizers. For instance, cold water fish seem especially sensitive to nitrates.

Precisely, however in the hobby, there are many that would like to clump all fish together and use that as a standard.

But why worry and fear so much when, 1#, they have no real data or idea about the commonly kept fish, and is all the extra effort and work really required?

Obviously not.

For our tropical, freshwater tanks, can somebody suggest some over-arching guidelines? Maybe not perfect, maybe there are species that are especially sensitive, but what might be max safe ppm levels (nitrate/phosphate/trace) for the average aquarist keeping the most common fish/shrimp/snails?

Yes, I'd say CRS's are an ideal critter for this test.
Which is to say, they do well at normal EI dosed tanks and bred well there.
Shrimp are generally far more sensitive to metals and NO3 than any fish.
And we can breed them and cull the lower grades like flies........

Tom, it sounds like you have done some of these tests and have some data. Otherwise, anecdotal evidence from others could be used to determine at what levels of various fertilizers they have had with healthy fish.

Also, do we need to consider cumulative effects of multiple ions? Would TDS be an important number to track, or do we need to only track individual ingredients?

Thanks again!

TDS is just a general measure, it is not specific.
Generally, as you add more different ions, the effects of say NO3 decrease.
Same in general. This is because the effects of one species of ion may now have a counter ion that helps mitigate the other toxic one of interest.

But you are correct about multi ion parameters in our tanks.........but fortunately it's less toxic, not additive etc in most cases.

You have to be willing to kill the fish and be able to good fish and shrimp keepers before you can test anything however. and that's a big problem for many, read any fish or shrimp only board without any plants, you will see plenty killing and having trouble with their shrimp etc.

It's only when you can grow the plants, breed the fish shrimp etc like flies/weeds etc, can really compare.

You need a good control to compare to.
You need to make sure there test you try are independent of the other parameters, like food, temp, filtration, K+, Na+, Cl_, KH etc etc etc..........

If everyone is growing, breeding and you have 40ppm of NO3..........
then no matter what, assuming things are independent, 40ppm in and of itself is not likely to be the cause.

But if someone is not able to replicate it because they stink at fish keeping, then the results are tainted.

You have to have success with culturing the biota to test it.
Most that are having troubles and complaining on line and talking about, do not do so because they have too many successes, rather, they have failed.

You should look to those that are able to breed them, and have plenty to sell.
Same with plants. Then see what they are doing.

Regards,
Tom Barr