Please visit our Sponsors
FAQs on Marine Water Quality involving Nitrites, Science

Related Articles: Nitrite, Ammonia, Nitrates, Establishing Cycling, BioFiltrationPhosphate, Silicates, Phosphate

Related FAQs: Nitrites 1Nitrites 2Nitrites 3, & FAQs on Nitrite: Importance, Measure, Sources, Control, Chemical Filtrants, Troubleshooting/Fixing & Nitrates, Ammonia, Phosphate, SilicatesChemical Filtrants

A/the "nitrogen cycle" encompasses dynamic activities... ever-changing... with circumstances, biological, chemical and physical interactions

Stubborn Nitrites... Another case of zip [HPO4]       5/8/17
Hello Crew! Thank you for all of the advice over the years. Your site has been an invaluable resource.
<Ah, good>
I'm having a problem with stubbornly high Nitrites after (during?) a cycle for a quarantine tank and I'm out of ideas.
<Well; quarantine systems tend to be unstable, disallowing establishment and ready metabolism of beneficial microbe populations... Do you have sufficient biomedia, circulation about it to sponsor nitrification?>
QT is 20g, HOB BioWheel filter with bagged carbon and GFO (there was a Phosphate issue from uncured dry rock in the display tank).
<Is there still "some" soluble phosphate present? You NEED some for microbial conversion of Nitrite to Nitrate... Re-read that last statement>
Also has a small skimmer as I intend to follow the mantra "Quarantine everything, corals and all" with this new display tank (150g). QT is bare bottom except for some pieces of pvc for hiding spots and tests at 0 Ammonia, 20 Nitrates, 2 Nitrites, 0 Po4,
<Bingo: Here's at least part of the problem. Remove most/all of the GFO>

480Ca, 9dkh, and 1250mg.
We use water from the display tank for water changes (was an attempt to seed, but also a way of acclimating the critters to heir eventual conditions. Currently the only inhabitants are 3 Scarlet Reef hermits.
Nitrates are coming down (artificially high from early on when the both tanks were showing 100+ Nitrates.... DT now shows zero after water changes and a little impatient Vinegar dosing).
<Won't help>
What is NOT moving however are the Nitrites. They've been floating between 2-3 for weeks. The QT has been running for almost 2 months and they just won't come down. I've tried everything. I've even added SeaChem stability to the area behind the Filter wheel in an effort to directly add <sic, aid?> the bacteria necessary. It just won't come down (but isn't going up either). We are doing water changes, but only @10% weekly. I know that a
bare bottom tank takes longer to cycle, but this just seems absurd. I would have expected a spike and then drop over a longer time. Not a constant 2-3ppm with no movement. The kit is Salifert, brand new, and tests fine at 0ppm on the DT as well. I'm completely out of ideas. Any thoughts? I know Nitrites are not as bad for marine organisms, but I'm not relishing the thought of subjecting a really cool frag to Nitrites just because I can't get this thing to fully cycle.
<Your situation is very commonly misunderstood. "Some" phosphate is absolutely necessary to all life... part of DNA, RNA, Phospholipids in every cell... ADP, ATP energy transfer molecules... AND conversion of NO2 to NO3... The (over) use of chemical filtrants has killed more livestock than pathogenic disease. Remove the rust and you will find your nitrite gone in short order>
Thanks again!!
<Glad to help Frank. Bob Fenner>

NO2 Confusion      7/26/12
Hi Crew,
I am currently worried about a Nitrite reading of 0.25mg.l (as you know virtually equals 1:1 with PPM) where as it this article in the subject line it states 344PPM for a 50% mortality rate with clownfish.
<...?! Takes much less than this>
Are Nitrites therefore made a great more of in regards to toxicity than they need to be for the marine hobbyist?
<What? No... are debilitating at any measurable concentration, deadly so at high pHs...>
I would like to help your readers with ammonia problems as I was running my tank at 28C but have reduced it to 25C FOWLR for a while as I have a very slight ammonia level just about detectable
What are you thoughts?
<They're posted... on WWM, in articles, books... NO2 is as toxic as NH3/NH4OH under various circumstances>
<Bob Fenner>

Comment for Neale (Nitrite toxicity; RMF, stuff you may want to comment on)  10/21/08 Dear Neale, I hope you and the rest of the Crew are well. I wanted to ask you about a post I read today that you answered regarding a trigger and a tank with 0.2 ppm of nitrites. In your answer, you stated that the nitrite level was deadly and that few marine fishes tolerate any level of nitrites for long. <That was certainly my understanding... until now, perhaps!> Now, I worship WWM and particularly enjoy reading your answers every day, but everything I have read suggests that nitrite is actually harmless in marine aquaria except at almost impossible to achieve levels. For some reason that escapes me (I am no scientist), there is something about marine aquaria/fish that makes this situation much different than in freshwater aquaria/fish (in which case/es it is indeed deadly at any level). <It has long been reported (e.g., in the Interpet Manual of Fish Health) that sodium chloride (the dominant mineral in sea salt) detoxifies nitrite and nitrate, which is why it had often been used as a "tonic" to help freshwater fish in badly maintained aquaria. Extrapolating outwards from that to say marine fish are essentially unharmed by nitrite at even quite high levels does make sense.> I was wondering if you could bring some clarity to this issue--it's a frequent point of contention on the message boards. From what I have read, nitrite in marine aquaria is indeed a problem, but only because it is an indicator of an immature/inadequate bio-filter and/or an overstocked aquarium. www.reefkeeping.com/issues/2005-06/rhf/index.php Thanks! Andy <That study seems pretty conclusive, though Bob Fenner may have different opinions, and I wouldn't put myself up as any kind of marine fishkeeping guru! Most of my marine fishkeeping experience is with coldwater stuff at university, lab animals such as snapping shrimps and mantis shrimps, and some reef and fish-only display tanks I've helped maintain over the years. In my defence, my instinct in this case was that the aquarist had two fish in a tank that was far too small for them, one of which was showing clear signs of stress. My assumption would be problems with water quality, and that nitrite was detectable would seem to corroborate that. So whether or not nitrite is the thing harming this fish, it's certainly a clue that water volume, overfeeding, lack of filter capacity and so on would definitely be issues for the aquarist to review. Or put another way, nitrite in marine tanks may be comparable to pH in freshwater tanks: in itself not a critical factor, but pH is revealing about the stability and type of water chemistry conditions in the tank, and these things do indeed directly affect the fish. Anyway, fascinating stuff, and thanks for writing! Neale.> <<Mmm, I do want to chime in... a bit... and do agree that it is NOT the presence of nitrite per se that is/can be a matter of concern directly... rather than as Andy and the article state, much more so the indication that the given system is not "well-established" to "bump up" or accommodate if you will, further loading on the forward reaction of nitrification. Still the "window" of measuring, measured nitrite is useful, should be heeded as a warning to suspend feeding, further stocking. RMF>>

Question about nitrites during fishless cycling, BioSpira f'  1/25/08 Hello all, <Hi Allison, Jeni/Pufferpunk here> A hopefully quick question for you. I have a new 30 gallon freshwater tank which I set up about 2.5 weeks ago (no fish), when I added about 1.5 ml of some ammonia I bought at the grocery store. It didn't tell me what concentration it was, but I read that "Household ammonia is a dilute mixture of 5 to 10 percent ammonia gas in water." My water indicated about 2.0 ppm ammonia. <Should raise it to 5ppm.> It took about a week before my ammonia went down to zero, and since then I've been adding a little bit each day (about .5 ml) and it's always at zero when I test it again the next day (and then add more). I haven't tested my nitrite until tonight and it's reading around 2.0 ppm, though I can't be sure because it's a color test. I would have thought the nitrite would be at zero by now, since it's been a week and a half since the ammonia first went down to zero. Could it be that the ammonia I'm adding daily is killing off the bacteria that does the second part of the cycle (the nitrite-to-nitrate part)? <No, that bacteria feeds off ammonia.> I was hoping to be able to get my first two fish (two Cory cats) in a couple days but I want the nitrite to be at zero, of course. Should I continue adding my .5ml of ammonia each night and wait for the nitrite to get down to zero? <You need to start out with enough ammonia to test 5pp, ammonia. When you start seeing nitrite, you cut that amount in half, until ammonia & nitrite are 0 & the nitrate spikes. Then do an 80% water change & you're ready to add fish (you can fully stock your tank at this point).> If you advise to NOT add ammonia, how then can I keep the bacteria multiplying? <All the bacteria will die without "food'"> I don't know of anywhere to get Bio-Spira locally, otherwise I'd just get that and the fish all at once! <Unfortunately, I have seen way too many instances of folks counting on Bio-Spira to cycle their tank, only to find out it wasn't kept refrigerated from Marineland, to the supplier, to the wholesaler, to the LFS, to the tank. I have a friend who is a wholesaler. He went to a supplier's warehouse & there were huge skids with cases of Bio-Spira, sitting out in their very warm warehouse. They had been there for quite some time. I was at a LFS one time, where they had some Bio-Spira out on their counter. I insisted it was to be refrigerated & they should read the directions on the back of the package. They read it & put it in the refrigerator for sale. It had been on their counter for months! I am getting a lot of reports of folks depending on their tank being cycled with Bio-Spira & after putting precious, sensitive fish (like puffers) into their supposedly cycled tank, losing these fish to ammonia/nitrite poisoning. I'm sorry I for being so long-winded in your particular email but I wanted people to know about this growing problem with Bio-Spira. If it isn't kept refrigerated the entire time, before getting to your tank, bets are, it's not going to work. One way to prevent this problem is to buy online from a place like Drs Foster & Smith. They guarantee cold delivery. Good luck with your fishless cycle. Here is an excellent article: http://www.thepufferforum.com/forum/library/water-filtration/fishless-cycling/ ~PP> Thanks for the help! I really appreciate it! Allison

Re: Question about nitrites during fishless cycling 1/27/08 Hey Jeni, <Allison> Thanks for the help. That's a nice simple formula to follow for a fishless cycle. And thanks for the interesting info on Bio-Spira...I guess it's better to do it the old-fashioned, foolproof way to be safe. <At least you can be sure that way! I'm very disappointed at the state in which some Bio-Spira gets to us... Glad I could help. ~PP> Thanks again! Allison

Nitrite Levels and Puffer Fish  8/11/04hi <Hi, Pufferpunk here> Just recently I have stripped down my tropical tank and made it into marine.  I brought all my equipment of a friend who was selling up. He kept all of the living rock and coral sand living with the fish.  The nitrites went high then went to zero now they are going back up again.  The fish I have are one regal tang one clown one green Chromis and one porcupine puffer. The tank is Rio 125L filters are the standard Rio filter with a 1000lph power head, fitted and an external filter of about 600lph turnover. I also have a SeaClone protein skimmer.  Should I worry about the levels of nitrite being produced because of the fish or will they be ok while my tank finishes its cycle, is there anything I can do to help this situation and the fish along? <I never suggest cycling a tank with fish in it.  Ammonia & nitrItes are extremely toxic to fish.  Living in toxic water will compromise their immune systems & can cause permanent damage.  Porc puffers especially, are very susceptible to ich, brought on by a lowered immune system.  I highly suggest finding some SW Bio-Spira to finish cycling the tank immediately.  ~PP>.               cheers Andy.

Question on Nitrites I did a water test on Nitrites yesterday ( just bought the test kit) and it is very high. <Ummm, what's missing here? How high is very high?> My ammonia level is zero. I read that water changes can help the high level on nitrite. Today is the day that the water change was due so I did it and both test came out the same as yesterday.  <Yes, water changes will likely forestall cycling... only temporarily dilute nitrites> I have 3 green Chromis and 1 yellow shrimp goby. Could this be cause by the liverock and how can I lower this level ? I have 45 lb of Fiji liverock in a 55 gal tank and I filter my water. Lianne T Carroll <Yes to the possibility of causes... Lowering really a matter of time going by... don't feed at all, or attempt to alter water chemistry, physics if the NO2 is anywhere near 1.0 ppm... Read over the "Biological Filtration" FAQs on www.WetWebMedia.com Bob Fenner>

Re: Question on Nitrites Sorry my mistake. By very high I meant between 2.0 and 5.0 ppm. The color is hard to tell which one it is. Either way deep purple is bad and light blue is good. Someone else also told me that not feeding for a while is good. Thanks for the info I'll read the FAQs. Hey I deserve this for being new to the trade. haha Thanks Bye Lianne Carroll <Yikes, this is VERY high indeed... please review what I have stated, chat with others, look through your reference works... and DO NOT feed or attempt to alter your water chemistry... other than executing a large (if you have the water pre-mixed) water change... like 50% soon... and again in a few days if the nitrites are still above 1.0 ppm. Bob Fenner>

Nitrite Hello Bob, I am having trouble cycling my 130 gallon tank. It has been over 5 weeks and I still have high levels of nitrite. Ammonia is zero, and nitrate is currently 5 ppm, but last week it got up to 20ppm. I currently have 1 black molly in the tank which has been doing fine. There is an outbreak of diatom growth, but apart from that nothing else. <Diatoms are completely normal.> I feed sparingly, almost not at all (diatoms are keeping him fed). The tank is kept at about 25 degrees Celsius, <That is ~77F for the Metrically Challenged.> with 9.5 hours of two 150watt MH per day as light. I have changed 60 liters at the most and this seemed to have no effect. <~15 gallons, would have a minimal effect on 130 gallons, about 5%.> Just yesterday I modified my trickle filter so it had some biospheres as well as the plastic hair rollers in it - I thought perhaps there wasn't enough substrate for the bacteria. Apart from these observations, the only thing I can add is that the pH is a little high - 8.6, as I was dosing baking soda a while ago ( learnt from my mistake). Could you suggest any reason for the prolonged wait for Nitrobacter to proliferate ? <Nothing to worry about. One to two months is normal. -Steven Pro> Cheers, Andrew Hough

Become a Sponsor Features:
Daily FAQs FW Daily FAQs SW Pix of the Day FW Pix of the Day New On WWM
Helpful Links Hobbyist Forum Calendars Admin Index Cover Images
Featured Sponsors: