buffering

In order for your nitrogen cycle to show that it is working properly you MUST have nitrates in your tank. It is the end product of the nitrogen cycle. The fact that you are not showing any indicates a bad test kit, or that your cycle has not completed itself.

RTR, I am like you when it comes to nitrates. But then with my planted tanks I don't want anything over 10 ppm anyways. You may have heard of Diane Walstad who is a professor at one of the universities in North Carolina. She is a proponent of the low tech planted aquarium. She claims that her tanks routinely test out at 100 ppm or better with no ill affect on her fish. She quoted a study that showed levels exceeding 2500 ppm were not toxic to fish. I think the jury is still out on this, but it makes for interesting reading.
 
I do not worship at the church of Ste. Diana. I admire and acknowledge the work she put into researching original references from the peer-reviewed literature, but I find some of the conclusions to which she jumps from that research mind-boggling.

For instance, nitrate alone is at least an order or up to two orders of magnitude less toxic than nitrite or ammonia, but its toxicty is long term, not short term as is the case for the other two nitrogen metabolites. The conclusion the 2500 ppm is non-toxic is on the face of it, absurd. But I do not have the original paper to critique, so have no idea what conditions they used (10 minutes exposure in a low TDS water?), but I would pay money to anyone who will show that they can breed a variety of fish and maintain them for a full lifespan in elevated nitrate water.

Besides which, in the real world, the issue is not nitrate alone. The issue is general build-up of pollution in the tank, of which nitrate gets the rap and serves as indicator because it is the only one of the hundreds of waste products for which the hobby has a cheap and easy test. We use nitrate as an indicator, not because it is the only waste product causing harm - which is exactly why all the folk tring for nitrate-removal by chemical or snake-oil techniques are kidding themselves. All they accomplish is to hide their pollution level behind a low nitrate titer.

Off of soap-box, returning to normal crabby old man mode. ;)
 
Well said RTR, well said. I believe the study she was referring to was done using Rainbow Trout as the test subject and the LD50 threshold was around 1300 ppm. There were other fish in the study, mostly game fish, and the LD50 numbers ranged anywhere from 500 ppm to over 2500 ppm. The only aquarium fish used was the guppy and it had one of the lower LD50 numbers.

Edited to reflect more accurate numbers.
 
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There is a huge difference between an LD50 and being non-toxic, massive. If Ms. Waldstad actually jumped to that conclusion, that is extreme even considering the source. I'll hope that it was misinterpretation of her remarks.

The toxicity of all the nitrogenous metabolites is tremendously variable between various species of fish, that is no shock to anyone. There would be no "cycle" fish if it were not. There is also a large component of habituation and adaptation to the acute versus chronic toxicity of dissolved nitrate - there would be no OTS if there were not.
 
I hope I can do this without breaking any laws but here is an excerpt from the discussion over at Aqua Botanic that i was refering to. The following is a quote from Diana Walstad in response to a question about nitrate toxicity.

"I was just passing through library today and serendipitously got the toxicity values (LC50) for nitrates from separate scientific studies for the 5 following fish species.

Salmon 1,310 ppm
Rainbow Trout 1,360 ppm
Channel catfish 1,400 ppm
Bluegill 420-2000 ppm
Guppy 180-200 ppm

These values are in the textbook 'Fundamentals of Aquatic Toxicology' and the author states that nitrates are "considered to be essentially non-toxic". I would agree.

As to reducing nitrates in aquariums, water changes aren't the only mechanism. I found that soil and/or mulm (no plants) will remove nitrates from the water. I'll talk about this at the AGA Convention.

There's a lot of folklore in the aquarium hobby. I know that my Rainbowfish do fine at 100 ppm nitrates. I think that it's secondary factors (introducing diseased fish without quarantine, salt buildup along with nitrates from infrequent water changes, filthy tanks) that sometimes accompany high nitrate levels.

I let fish behavior (eating or not?) and plant growth (growing or not?) determine what water chemistry is detrimental. If my fish don't eat, then I immediately take corrective action- change water, clean filter, and add fresh carbon to filter."

Diana Walstad

RTR, I posted this in an attempt to make sure I didn't stick my foot in my mouth. :) I have learned a lot from reading your posts since I have found this site and I have learned from your responses to this topic.

Moderators, If by posting this quote from another site I have violated any rules please accept my apologies and delete it at once.
 
Karnaaj said:
The following is a quote from Diana Walstad:
I let fish behavior (eating or not?) and plant growth (growing or not?) determine what water chemistry is detrimental. If my fish don't eat, then I immediately take corrective action- change water, clean filter, and add fresh carbon to filter."

Diana Walstad
Click to expand...
While I don't exactly have the street cred. to put much weight against what she sais, this seems like a sloppy approach to fish keeping.

Sure, I keep track of fish behaviour and plant growth, but to gauge my tank maintenance by a problem appearing would be irresponsible, IMO. I think that it's far more appropriate to maintain a tank to prevent illness/problems, as opposed to treat them. Yes, certainly if something is wrong with my fish I'll step up my maintenance, but I think that a preventative or proactive, rather than reactive, approach is more responsible fishkeeping.

JMO
 
Thanks for the post happychem. Btw I have enjoyed reading your posts on water chemistry, they have certainly cleared up some misunderstandings that I have had. :D
 
That sounds reasonable to me on the data presented, but it still does not specify acute or chronic - I'd have to see the original documentation.

The conclusion that nitrate is non-toxic after giving a measureable LD50 for the one tropical suitable for hobby tanks, and that level being one which is (unfortunately) not rare in OTS threads, plus that fish (guppy) being on of the hardiest of the tropicals, sort of boggles the mind that a conclusion counld be drawn about toxicity in hobby tanks. She does modify it a tad by blaming the rest of the pollutants, which is actually fine - but to release nitrate from any guilt/responsibility is not, repeat not, supported by any evidence presented here - rather the opposite. Which is exactly the issue I have with her whole package. Pesenting valid peer-reviewed data, and then using that data in non-comparable situations, and saying that it supports conclusions which it does not do - well, whatever you want to call it, it ain't science. One term which could be applied would be "snake oil".
 
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