ray-the-pilot

“Since we're talking fertilizer here, most often from KNO3 and not nitrate in any form”

I'm confused? Isn’t KNO3 Potassium Nitrate?

Anyway,

Even using your data remember, that a LC50 of 180-200 ppm does not represent a safe level. This is the level that will kill 1/2 of your fish. You would really like to be 1/10 or 1/100 below this level for safety.

The LD50 listed in Wikipedia for KNO3 is 3750 mg/Kg, which converts to 3750 ppm. While it doesn’t state the species, I presume that data is for mice.
Based on your numbers, fish are 3-9 times more acutely sensitive to Nitrates than mice.

The numbers developed by the US EPA are not derived from acute studies they were derived from long term epidemiological studies.

I agree, that 60 ppm of NO3- may not “immediately” kill your fish based on the acute data; however, long term, that is not a healthy level for your fish.

Philosophos

Somehow the word "other" got lost in my typing/editing. Most ferts use KNO3, some use a bit of urea along side it. I've never considered urea the brightest move for fish in the first place given the nitrite.

What I'm wondering is how you know it'd be 1/10th or 1/100th in this case. I wasn't saying that 180-200ppm was safe for these fish, I just figured it'd be good to have a reference as to what toxic levels actually are. I think the evidence presented by anyone in this thread fails to show any solid indication or lack there of when it comes to chronic toxicity over the course of a fishes life.

Personally I like the concept of sustainability; everything after that is aesthetic when it comes to an aquarium. If the fish can be spawned and hatch out fry that can be raised to maturity in the same tank, then the level of a chemical clearly isn't toxic enough to prevent population growth.

LD50 tends to indicate ingested or injected (intramuscular or intravenous) levels; the actual concentration within the animal its self. LC50 in aquatics indicates a submersion in most cases; column levels, not internal. So the LD50 of an aquatic organism is most often different than the LC50, and may be higher or lower depending on the chemcial involved.

-Philosophos

ray-the-pilot

You’re right, 1/10 or 1/100 are rather low safety factors.

The LD50 for cyanide is about 10mg/kg which means that if you gave 10 adult males weighing 70 Kg a 700 mg dose about 5 on average would die.
If you gave 10 adults weighing 70 kg a 70 mg or 7 mg dose I’m pretty sure you would run out of volunteers pretty fast.

The standard safety factor in the pharmaceutical industry is 1/1000.


Well, I agree! If you can point to some scientific evidence that supports this opinion, I’d go along with you. Do you know of any long term studies that show fish can be kept at 60 ppm of nitrate with no ill effects?

I think the body of opinion on this is the opposite.

Here are a couple of sites that say high nitrates are bad for fish.

http://freshaquarium.about.com/od/wa...a/nitrates.htm

http://www.aquarium-pond-answers.com...-nitrates.html

Now my feeling is that the ideal level of nitrates should by close to what it is in nature about 0. This is impractical when growing plants; so, I have to compromise. I rigorously control the nitrate levels of my tanks to be below 20 ppm and try to maintain it closer to 10 ppm. I have no problems growing plants at this level. (In fact they grow way too fast at this level). Anything higher than this would only unnecessarily stress my fish.

I'm not sure I understand this: There is no benefit to keeping nitrates high so why are you telling people that it is OK? There really is a lot of evidence indicating high nitrate levels are not good for people or fish. If you don’t believe me just scan the internet for nitrates!

Philosophos

Again, this is using mice and humans as examples. I don't believe the pharmaceutical industry maintains safety factors at any fixed rate; it's a matter of liability and profit from what I've seen. I'm not saying you're not right, I'm just saying that I'd like to see some testing done within the hobby. I've seen pictures of tanks with discus spawns at 40-50ppm NO3.

Check the section on nitrogen as nitrate in this paper:
http://www.aseanenvironment.info/Abstract/41013039.pdf

This is a good one, too:
http://www.waterboards.ca.gov/water_...08/ref2426.pdf

You'll notice in this study that long-term LC50's for trout and salmon were very high, the NOEC low, but that's cold water. Take a look at the warm water fish, including 164 day NOAEL's (no observable adverse effect levels) for channel catfish around 90ppm among many others.

You really need to watch whether the source for your reading is talking about organic or inorganic nitrate, and what form it's in. KNO3 is a very far cry from more toxic nitrogenous compounds. I agree that 20ppm of NO3 through fish waste and nitrification is going to come along with some organic compounds that aren't so hot for fish.

These are sites, yes, but not studies. They aren't even home experiments. These are opinion pieces with a real lack of sourcing.

If you prefer a more hobby related direct experience sort of thing, here's one:
http://www.barrreport.com/34434-post2.html

There are altum and discus spawns in these tanks. If i remember right the owner of the discus tank keeps the levels around the 45-50ppm NO3 range.

Keeping nitrates close to zero because this is what they are found at in nature is an argumentum ad naturam. I don't think nature creates the ideal circumstances for animals, and I don't think animals evolve to create perfect adaptations for their environments.

When I dose 15ppm I find my NO3 levels fall to 5ppm, so I dose 20ppm plus feeding and I find the numbers sit around 10-15ppm. This is in mid to high light tanks of 2-3wpg of CF with a high density of plants.

I'm not telling people to keep nitrate levels excessively high, but I'm also not the sort to draw conclusions from unrelated evidence. I have seen more direct evidence to the contrary in both studies and experience. At the same time, I happen to believe in non-limiting nutrient levels, so I advocate what ever dosing it takes to get there; 10-20ppm is quite an easily maintained target range. I've kept my tank at 20-25ppm through multiple A. hongsloi spawns with no ill effects that I could observe. The mother was far more of a danger to the fry than the water.

-Philosophos

ray-the-pilot

Well based on your previous post it seems that we pretty much keep our tanks at the same relatively low level of NO3; so we agree on that!

Can I point out a few things?

In this hobby people make statements that are completely unsubstantiated. This is not meant as a criticism of you and please don’t take it that way. It is more that the hobby needs to be more critical of what people claim so that real evidence can be accumulated.

Again, these are not criticisms but some suggestions:

Firstly you posted two links. This is one of the best things that we can do to help improve information in the hobby. Being able to go to a source to check out something that someone claims is the first step in getting reliable information. Unfortunately there are some problems.

This link to the California State Water Resources Board goes no where:

http://www.waterboards.ca.gov/water_i...08/ref2426.pdf

The second link (I’m not sure of the original publication), which is supposed to be a research paper on “long term studies that show fish can be kept at 60 ppm of nitrate with no ill effects” is actually a survey paper (secondary source) and not a research study (primary source). This link does not support the position that any fish can be kept at high levels of NO3 for long period. In fact the opinion of the authors is that for aquatic ecosystems the level of nitrates should be below 4 ppm (1 mg TN/L).

In addition, the data presented (for 12 species) demonstrated that all of these organism showed some observable ill effects in as little as 30 days at levels above the USEPA guideline of 10 ppm N03 –N/L


The authors state:
It is concluded that levels of total nitrogen lower than 0.5–1.0 mg TN/L could prevent aquatic ecosystems (excluding those ecosystems with naturally high N levels) from developing acidification and eutrophication, at least by inorganic nitrogen pollution. Those relatively low TN levels could also protect aquatic animals against the toxicity of inorganic nitrogenous compounds since, in the absence of eutrophication, surface waters usually present relatively high concentrations of dissolved oxygen, most inorganic reactive nitrogen being in the form of nitrate. Additionally,human health and economy would be safer from the adverse effects of inorganic nitrogen pollution.

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

Lastly, and this is a really big problem on this board, posts on these boards should completely avoid unsupported hearsay like, “I've seen pictures of tanks with discus spawns at 40-50ppm NO3.”

As for me…I’ve seen pictures that show that there is a gigantic whole in the earth near the North Pole but I’m not sure what that proves.

It is OK to say, “I've kept my tank at 20-25ppm through multiple A. hongsloi spawns with no ill effects that I could observe.” since that is a fact that I observed. This allows people to review the facts by asking me questions such as: “How did you measure the levels of NO3.”

If everyone followed these suggestions, real substantiated information can be passed on.

OK this is my last comment on this thread. You can reply and have the last word but as for me I think we pretty much covered everything.

RTP

Philosophos

Yup; I see no reason to be inefficiently excessive. It's a waste of money, and if I'm wrong, the excess nitrates won't help either. On the other hand, if plants demanded 40ppm I'd probably be pretty comfortable there as well.

Oh I agree. Some of the stuff you bring up later on is precisely the sort of thing that I see others think of as good evidence. I've actually caught crap from mods, had warnings issued and had my posts deleted on other sites for challenging someone more experienced but with no evidence or understanding of the topic on which they spoke. So at this point, I toss a little in to pander to those sort whether they be the ones I'm speaking to, (or in this case) the ones who may be reading. I can't fix people's thought processes on these forums, but I can try to reduce the amount of bad information that gets passed around for the wrong reasons.

Yes, I tend to read a ton of journals because I also advocate the process of peer review; I've got piles of folders and bookmarks just for studies related to the hobby.

It's fixed now; there was an "h" missing in the http:// part of things.

It's not primary source, but it relies on a ton of studies you can look at for your self. I have a feeling ichthyologists should be able to determine a long term LC50 and such without much issue.

But it does show that there are species that can endure levels like 90ppm without any apparent harm; that's what a NOAEL (No Adverse Effect Level) is. You'll notice that the little 2-8ppm LC50's and such are actually related to cold water salmo and oncorhyncus spp. which are known to have lower nitrate tolerances given the slower degredation of waste and the colder, cleaner water found in the natural habitats that they evolved within. This does not apply to warm water fish, but it was these cold water levels that precisely influenced the authors concluding opinions.

And all for the reasons that I have linked above. Their statements were based on the compilation of all species, not the ones more similar to what we're looking at within the hobby.

That statement was to deal with the sort of people who only take that evidence. The tank does exist though; it's right here:
http://www.barrreport.com/estimative...html#post34434

You'll find a number of other posts by Tom on the issue of NO3 toxicity, this being one of the better:
http://www.barrreport.com/articles/3...html#post18245

If you can dig up the APD debates, I'm sure you'll find tons there as well.

It's okay, but it's not great. Again, this is one of those things I toss in because so frequently good evidence is rejected. For some reason people think it means more when I say it's my tank and my fish, and they actually trust my unverified opinion. I shake my head, but I post it anyways. Mind you, I wouldn't go to the lengths of omitting decent evidence; pandering to flawed thought for better results is one thing, ignoring good critical thinking is another.

Oh, the NO3 test was a multi-point calibrated red sea kit; I determined 20-25ppm roughly through matching the shade of it.

I honestly hope it's not. I disagree with some of what you're saying, and I wouldn't mind seeing if you've already got what I've said addressed in your mind. This has been a more productive discussion than most of what goes on when two people disagree. I usually clench my teeth and wait for the moment when the staff have to get involved because someone is flying off the handle about their personal experience trumping the body of scientific knowledge. It's a sore subject for me if you can't tell

-Philosophos

Diana K

So, back to the original question:
Using the fertilator to guide dosing.

1) Test your tank (in this case for nitrates).
2) Figure out where you want to keep the nitrates. (See all the research reported above)
3) Use the fertilator to figure out how much KNO3 to add to raise the nitrates to the level you want.
4) Dose half that and test once it has all dissolved and circulated. Did it do what was expected? Fine tune the dose.

Next, test daily to see how fast YOUR tank (plants) use the NO3. Dose again as needed.

My experiences:
Before plants my tanks would regularly get to 40 ppm nitrate, and the fish were not happy. Not so colorful, not so active, more deaths than I felt was right. Ich happened occasionally.

After plants the nitrate is rarely over 20 ppm, and usually between 5-10 ppm.
When it hits 5 ppm I dose KNO3.
When it hits 20 ppm I do a water change.
Most of the time it stays pretty stable, though. Fish food balances plants' use, and the nitrate stays stable, or changes very slowly.

Plants are growing, fish are colorful and active.

I dose more potassium (KH2SO4) than nitrate or phosphate. I spread the dose out over the week. 3 days macros, and alternate with 3 days micros because I feel that the more stable conditions are better for fish and plants.

The fertilator is NOT telling you how much (of anything) to add to your tank.
It is telling you "If you add this much THEN you will see a rise of this much"
It is up to you to figure out (test) how much of anything your tank needs, and how often.