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FAQs on Marine Freshwater Quality involving Nitrates 2

Related Articles: Nitrates in Freshwater Aquariums, Establishing Cycling, Freshwater Filtration, Know Your Filter Media, A Concise Guide to Your Options by Neale Monks, Setting up a Freshwater Aquarium, Tips for BeginnersWater Quality and Freshwater Aquariums

Related FAQs: Nitrates 1, & FAQs on FW Nitrates: Importance, Science, Measure, Sources, Control, Chemical Filtrants, Troubleshooting/Fixing, & Ammonia, FW Nitrites, Biological Filtration, Freshwater Nutrient Cycling, Establishing Cycling 1,


0 ammonia, 0 nitrites, 160 ppm nitrates during fishless cycle      5/5/16
I am trying to cycle my 10 gallon tank (for a Betta) using the fishless ammonia method. It's been 6 weeks and ammonia and nitrites spiked and the fell to zero.
<Ahh; done>
My questions are: why are the nitrates so high,
do I continue to dose with ammonia (I have stopped)

will the nitrates drop eventually like the ammonia and No3 ?
<Mmm; slowly; yes; but better to either add some live plants... or do a significant water change... half the water, halve the NO3>
I have just done a 90% water change and nitrates are at 40 to 80 ppm. The tank has a HOB filter, a sponge filter with airstone, a heater and a UV sterilizer. The pH is 7.4, the tap water is hard (and 10-20 ppm nitrates).
There are some (3) plants and the roots of a philodendron in the tank. I plan on adding more plants. What do I need to do?
<Really; just be patient; time going by... Monitor/test every few days... NO3 will "go down".>
<Welcome. Bob Fenner>
Re: 0 ammonia, 0 nitrites, 160 ppm nitrates during fishless cycle      5/6/16

Thank you Bob Fenner!, should I be feeding the bacteria with fish food until the nitrates come down (just bought 4 more plants)?
<Yes; but really... "just a pinch" or a single flake or two per day. Takes very little to sustain a nitrifying population>
Thanks again,
<Again welcome. BobF>
Re: 0 ammonia, 0 nitrites, 160 ppm nitrates during fishless cycle      5/6/16

Great, thanks again for the info.
<Cheers Eve. B>

For Neale Monks, Nitrates      1/8/16
Hello Neale, and my best wishes for the New Year to you and yours.
<Thank you.>
I will be emailing separately my observations on the flashing/bacterial issue you helped me resolve (thank you so very much) but now I would like to discuss nitrates a bit if you would be so kind. I have frequently read your advice on keeping nitrates below 20 ppm, and naturally I recommend the same when I respond to members of the forum I am now on. I am being questioned on this, so I would like to understand it better.
<Sure thing.>
First thing to get sorted is the unit being used. The scientific community tends to use NO3 N-n, whereas most hobby test kits use total nitrates. I understand the conversion factor is 4.43, so for example the US EPA limit of 10 ppm allowable nitrate in drinking water which is NO3 N-n would equate to 44.3 ppm NO3 with our test kits. When you are recommending 20ppm as max for nitrates, is this the hobby test kit unit (I assume so)?
<Correct. No point citing something people can't (easily) measure at home.
In fact it doesn't usually matter what numbers you choose to use. Most of the nitrate kits I've seen will have some sort of card with them, and that card will be have on it a scale made up of a few coloured patches. The API one for example has seven coloured patches, from yellow (low) to red-brown (high). So long as you aim to keep nitrates closer to the low end of that scale where sensitive fish are being kept, and certainly below the medium colour/number on that scale, you're laughing. Actually knowing what the numbers are is not important. So for that API kit, yellow or orange are fine, red not good for sensitive species like dwarf cichlids, and red-brown probably too much, long term, for anything, at the very least a triggering factor for algae. Make sense?>
To the nitrates, then. Natural habitat waters of all of our fish (so far as I know) have nitrates so low it would probably be impossible to measure them with our kits.
<More or less, yes.>
In the fish, nitrate will act much like nitrite, making it more difficult for the blood to carry oxygen.
<So they say.>
I have come across studies, admittedly on mainly commercial fish and not ornamental, suggesting nitrate levels of 2 to 4 ppm NO3 N-N would affect the development of fry, and many fish and invertebrates will have difficulty with nitrate at 10 ppm NO3 N-N. This study is here:
You have mentioned cichlids likely being affected at levels above 20 ppm, and on the cichlid site it is suggested that nitrate above this may be the true cause of Malawi Bloat.
<Correct. That said, nitrate is complicated. The lethal level of nitrate for some fish experimented on (in labs) seems to be high, supposedly 100 mg/l or more. On the other hand, scientists have only tested a very few (big) species, farmed trout for example, and often their experiments are shorter term things, like how many of the fish die across, say, a week or a month. We're keeping a hundred different species often for years if not decades, so our experiences (and expectations) are different.>
The above is just so you have an idea of where I am with this issue. I guess at this point, I would be interested very much in your thoughts on this, and any evidence, studies, etc., to support our position [I have certainly taken yours ] on keeping nitrates low.
<It's complex. Nitrate isn't something I worry about too much keeping the sorts of fish I like to keep, such as catfish and freshwater livebearers.
Provided other parameters are good, fast-growing plants keep nitrate levels low enough risk of toxicity isn't an issue, and water changes can be carried out as/when required. But if I was keeping species like Dwarf Cichlids or Mollies (in freshwater) that are known to be sensitive to nitrate, in the sense that high nitrate has been associated with disease (bloat, shimmies, etc.) than I'd make more of an effort to monitor nitrate and pre-empt any high nitrate situations using low stocking, low food input, and frequent water changes. Most freshwater aquarists can, I think,
ignore nitrate unless they're (a) struggling to keep a possibly sensitive species; or (b) dealing with an algae problem.>
As always, looking forward to your wisdom, and with sincere appreciation.
<Hope this helps; by no means an expert! Cheers, Neale.>
Re: For Neale Monks, Nitrates      1/8/16

This is great, thank you Neale. Now I have some follow-up, concerning the effects/symptoms of nitrate on fish.
Many if not all of your answers to questions on PFK where nitrates are mentioned as being high involve lowering to no more than 20 ppm. From this I would assume that the effect of nitrate is much like so many things--a source of stress, weakening the fish, opening up opportunities for more serious problems.
<Correct, so far as I can tell. Nitrate isn't immediately toxic like
ammonia or nitrite. On the other hand, because high nitrate levels often go hand-in-hand with things like overstocking and infrequent water changes, it's hard to pick out any problems nitrate is causing from things like lack of oxygen and background acidification cause by nitrate and phosphate accumulation. Tanks with high nitrate levels tend to be neglected tanks, in the sense that the fish keeper has too many fish in them and does too few water changes. So there can be all sorts of reasons fish in those tanks are stressed, not just the nitrate. Make sense?>
One obvious that I assume would occur would be a shortened lifespan from the stress if nothing else. But are there any signs along the way that nitrate may be causing issues?
<None that I'm aware of, but some diseases have been associated with high nitrate level, such as Hexamita and HITH/HLLE in cichlids.>
A member on the forum today mentioned his fish being "fine" with 80 ppm nitrate (which is way into the red on the API card you mentioned) but his Firemouths remained quite pale, and he wondered if this was due to the nitrates. I would think this likely, do you agree?
<It's certainly a possibility. But I'd also observe that Firemouths are widely kept badly. Though territorial, they're bluffers, not fighters, and do badly with genuine fighting cichlids (pretty much all the Central Americans beyond Rainbow Cichlids) and are really best kept on their own with dissimilar tankmates (catfish, loaches, characins, etc.). They're also sand-sifters, so a tank with gravel would be wrong. Finally, like all cichlids, their colours will become paler if they're exposed to bright light from above and/or below. A dark, shady aquarium is better.>
<Cheers, Neale.>

Balloon belly mollies... Not... NO3 rdg.    1/17/12
I have a 20 gal tank 6 moolies,35gal Eheim filter, I do water change 10% every week. My nitrates are up over 40+.
<Too high by at least twice>
I have used nite zorb,it did nothing, I have a RO/DI system. What can I do about the nitrates? Thanks
<Read: http://www.wetwebmedia.com/FWSubWebIndex/fwnitrates.htm
and the linked files above. Bob Fenner>

Nitrates, FW   3/1/11
I have a 55g setup containing a Black Ghost Knife, an Oscar, and a Plecostomus.
<Far too many fish in very little water, plus the Black Ghost is sensitive to low oxygen concentration, and the Oscar sensitive to nitrate.>
The tank has been running for a little over a year now and the fish are producing more wastes resulting in higher nitrate levels. I do a weekly water chance to bring the nitrates to under 10 ppm but by the next week they are high again. I would ultimately like to get a 125g for these fish
but in my current living and financial state that is not possible.
<Very short term I'd rehome the Pleco -- adds nothing to this system. Algae better cleaned by hand, and all the Pleco does is dump solid waste into the filter, reducing filtration, while cranking out lots of ammonia.>
My short term solution would be to get another filter, maybe a Marineland Emperor because of the bio wheel.
<Won't have any effect on nitrate.>
Would the addition of another filter prevent nitrates from accumulating so much between water changes?
<No. Biological filters *make* nitrate. The amount of nitrate is proportional to the number/size of the fish. To remove nitrate you have three main options: fewer fish, more water changes, and/or less food. Denitrification in aquaria is difficult to do without considerable expense and engineering, and plants, while excellent nitrate removers, aren't going to make much difference in a tank this size/stocking density without very strong lighting and perhaps an external sump with plants in there as well.>
Also, my Plecostomus has hardly grown the entire time I've had him while my Oscar that I bought the same day has gotten huge. I realize the Oscar grows faster and larger but the Pleco hasn't even grown 2 inches in a year.
<Not getting enough of the right foods?>
I was thinking of adding some of the plant food that I use in my 29g planted African tank (Leaf Zone) to stimulate algae growth so the Pleco can have more food available. Thank you for your advice and opinions.
<More algae = more food = more nitrate. Hardly what you want.>
<Hope this helps. Cheers, Neale.> 
Re: Nitrates 3/1/11

Thanks, it does help. I just can't get a large aquarium yet, as much as I'd like to. I had considered rehoming the Pleco. I have 2 pumps in the tank to circulate water and detritus. The Ghost Knife loves hanging out right in front of one of them.
<Yes; they inhabit pools and rapids in the wild, so prefer (need, long term) lots of water current.>
I don't trust the denitrifying chemicals or units plus they are pretty expensive.
Both large fish are almost fully grown so hopefully it won't get much worse. If I got rid of the Pleco I feel I should be okay with weekly water changes.
<Possibly, but 55 gallons is really not much for an Oscar and a BGK; 75 gallons better, but 100+ gallons realistic for long term success.>
They both seem to get along fine given the amount of water that they share.
<Indeed, but they will both grow, and both are prone to slowly developing issues that aren't obvious. Oscars develop Hole-in-the-Head and Hexamita infections when exposed to less than perfect conditions. May takes years for it to become obvious.>
I got them about a week apart and I've never seen them fight. Actually the BGK and Pleco fight more, most likely because they occupy the same space.
<Likely so, and both are territorial.>
Thank you for your insight
<Glad to help. Cheers, Neale.>  

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