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FAQs on Marine Freshwater Quality involving Nitrates: Measure

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, Nitrates 2, & FAQs on FW Nitrates: Importance, Science, Sources, Control, Chemical Filtrants, Troubleshooting/Fixing, & Ammonia, FW Nitrites, Biological Filtration, Freshwater Nutrient Cycling, Establishing Cycling 1,

Do your own testing... note whether the kit is measuring Nitrogen as Nitrate or total Nitrate... with the three oxygens per molecule...

Ammonia, Nitrite & Nitrate Units of Measure     4/10/18
Hello Crew,
<Hey Ray>
I have a 210g, probably considered overstocked, mixed Malawi tank. The tank is filtered by a submerged media sump with a six times turnover. I use Hanna meters for my chemistry checks. The ammonia, nitrite and nitrate
meters all measure using the -N unit of measure (NH3-N, NO2-N & NO3-N).
The unit of measure for ammonia and nitrite are not relevant since the goal of both is to maintain 0ppm. Nitrate is the one causing me some thought. The tank consistently runs 10 - 30ppm NO3-N and I use this value to determine water changes, as it approaches 30ppm I do a 50% WC usually every other week. But if I apply the conversion factor (4.4) to these numbers my ranges are 45 - 130ppm in which case my WCs should be happening probably twice per week. I recently read the article, Nitrates in Freshwater Aquarium Systems
by Bob Fenner, which stated "Do check your test kit though almost all are nitrate ion types on the market nowadays..." I'm guessing doing the conversion on NO3-N > NO3 is what I should be looking at.
<Yes; agreed>
The tank has been running in its current configuration (mixed Malawi) for 2 years, before that it was a planted discus tank for maybe 8 years. Being retired gives me time to think, maybe too much. Should I take the attitude, "if it ain't broke, don't fix it?" Looking for confirmation/disagreement.
Raymond M Sugel Sr
<Were it me, mine, I would increase the number/frequency of water changes as you state (twice a week; with pre-mixed (for pH, salts if you use them) stored water. I encourage you to look into the possibility of tying this
tank in with a good size/volume sump as well, perhaps growing live plants there, incorporating a deep sand bed for denitrification; utilizing and out-gassing the excess NO3. Bob Fenner>
Black Ghost Knifefish; hlth., NO3 file       11/24/17
Hello Crew,
Stumbled onto your site, read some stuff that sounds very helpful.
I have a large about 30cm long single BGK fish, I had it now for a few years in a 645Ltr. mostly African (both Tanganyika/Malawi) a pair of buffalo heads, clown loaches and Chinese Glass cleaners.
<Quite a mix>
All doing well.
At one stage awhile ago I was concerned about Nitrate/ Nitrite but have given up, could not get it right, hence small regular water changes, water always clear, no diseases, fish have been happy, some have bred
For some reason I have noticed BGK with swollen belly not eating, see him more often than not. Hangs vertically near the water outlets from the filter & not in usual hiding hole. BGK fish was large when I bought him, could he be getting old? But why the swollen belly?
<Perhaps "just" over-eating... could be a blockage, tumor... even a bacterial et al. infection>
I would greatly appreciate any advise regarding my Black Ghost Knife fish, he’s cool.
<I'd read on WWM re NO3; endeavor to keep it under 20 ppm via various methods, introduce a "laxative" food item (e.g. Daphnia, Artemia) to the BGK for a week or so. Bob Fenner>
Re: Black Ghost Knifefish     11/29/17

Thank you Bob,
<Welcome Gavin>
Knife fish died. I'm thinking tumor or blockage. I don't feed fish for days at a time sometimes due to shifts I work.
<I see>
Appreciate you getting back to me though.
Thanks again
<Thank you for this follow up. BobF>
Re: Black Ghost Knifefish; now Nitrate f' as well     11/29/17

Hey Bob,
Any tips for getting the Nitrate down?
<Ah yes; avoidance from the get go, water changes, biological amelioration, chemical filtrants. Gone over in detail here: http://www.wetwebmedia.com/fwsubwebindex/fwnitrates.htm
and the linked files above>

It's got me beat, the Ammonia reads 0 ppm to 0.25 ppm if that, as I stated previously I do regular water changes, vacuum the substrate but the Nitrate stays up.
Have tried a little bit of Poly-Filter about the size of the Ammonia Test kit box as recommended by the Aquarium place I bought it from.
<A worthy product>
But if the fish (Electric Yellow & leleupi) have laid eggs their got to be happy right?
<That or stressed; either end of the spectrum elicits reproduction, reproductive behavior>
Up until the Black Ghost Knife fish became crook I've had no problems.
<And you, Bob Fenner>
Re: Black Ghost Knifefish     11/30/17

Thanks again, Bob really appreciate your help.
I will have a read of that site you forwarded.
Kind Regards
<Real good mate. BobF>
Re: Black Ghost Knife fish; Nitrates f'      12/2/17

Righto' Bob,
Sorry to annoy you.
<Not an annoyance Gav. We're here to share>
I read the literature on the web site you forwarded, even though it mostly spoke of Marine set ups, it did in parts touch on Fresh water and in part mention the filter system.
That got me thinking do I NOT clean my filter regularly enough? Is the filter the reason my Nitrate/Nitrite is high?
<This is definitely a possibility as source of NO3. Mechanical filter media, accumulating materials that can/do break down into Nitrate is a principal source of this nitrification product>
All most people say is do regular water changes.
I am under the impression don't mess with the filter, clean it when you notice the flow rate drop, say every 6 months.
<Mmm; well; we need to expand on our ideas, terms here. "Filtration" is a very large concept; for instance, it encompasses denitrification, a set of processes "in reverse" that convert Nitrate largely to Nitrogen and Oxygen... under anaerobic conditions. Are you aware of this?>
I use an Aqua Pro 2200 Canister Filter. The 3 sponges & wool in the bottom basket, the rest filled with Biohome Standard Media and a tray of BioBalls which is all suppose to allow for colonisation of bacteria's and alleviate
Nitrate/Nitrite problems with less cleaning time.
<Actually... you may want to investigate a bit more here. I would switch out the Bioballs and if you have more of the Biohome Standard Media or other sintered glass (e.g. Siporax) filter product, use it in the BioBalls space. These balls drive the forward reactions of nitrification too much, too fast. You will likely see a difference on their removal, substitution within a few days>
Should I be cleaning the filter more often? Have I got the filter set up wrong?
<Just the BioBalls part here>
In the tank it's self are two air stones (bubbles/water movement), a sponge filter, an Aquael Turbo Filter 2000 internal filter and I use it with just the sponge like a power head pointed from one corner of the tank to the
width of the tank so no dead spots (2 Ft..) more bubbles/water movement, right? Also an Eheim streamON+5000. Optimum water circulation with a natural, smooth current formation.
As I have stated previously, the fish seem happy, there colour is bright except for one has dulled since I bought him (was red, now more brown) one has completely change to a better colouring, Nice dark blue with a bright
yellow streak from his mouth through his Dorsal fin to his tail (a Hap).
There is lots of water movement and air ration in my tank I think Bob, so is the filter the problem? What do you think?
<Fishes and non-fish aquatic life can become accommodated to higher NO3 concentration over time... but I would still aim for a reasonable number. There are other mechanisms to control; e.g. live plants use, Deep Sand Bed (in the tank or a tied in sump/refugium), ....>
Once again, again thank you for your knowledge/ information.
<Like tools rusting in a basement, only worthwhile if employed eh?>
Kind Regards
<And you Gavin. Do write back if something is unclear, incomplete, or you have further questions. Bob Fenner>
Re: Black Ghost Knife fish; ongoing... NO3   12/6/17

Hello Bob,
I read the literature on the web site you forwarded, even though it mostly spoke of Marine set ups, it did in parts touch on Fresh water and in part mention the filter system.
That got me thinking do I NOT clean my filter regularly enough? Is the filter the reason my Nitrate/Nitrite is high?
<Might be a factor; best to only clean/change out "part" of the filter media at every interval. As an example, if you're using two units of Chemi-Pure let's say, take out the oldest one and leave the less old one, adding a new unit>
All most people say is do regular water changes.
I am under the impression don't mess with the filter, clean it when you notice the flow rate drop, say every 6 months.
<Mmm; no... better more frequently. Like every month for the mechanical media... the chemical should be switched out/some rotated for new about this same interval>
I use an Aqua Pro 2200 Canister Filter. The 3 sponges & wool in the bottom basket, the rest filled with Biohome Standard Media and a tray of Marine BioBalls which is all suppose to allow for colonisation of bacteria's and alleviate Nitrate/Nitrite problems with less cleaning time.
<We had this convo.... I'd remove the BioBalls, use ChemiPure in the space instead>
Should I be cleaning the filter more often? Have I got the filter set up wrong?
<.... Yes>
In the tank itself are two air stones (bubbles/water movement), a sponge filter, an Aquael Turbo Filter 2000 internal filter and I use it with just the sponge like a power head pointed from one corner of the tank to the width of the tank so no dead spots (2 Ft..) more bubbles/water movement, right? Also an Eheim streamON+5000. Optimum water circulation with a natural, smooth current formation.
<Okay; good to have more circulation, and aeration helps... most canister filters are deficient here>
There is lots of water movement and aeration in my tank I think Bob, so is the filter the problem?
<Not a problem, other than the driven nitrification from the bioballs, but could be improved as I've stated>
Once again, again thank you for your knowledge/ information.
Kind Regards
<Welcome. BobF>
Re: Black Ghost Knife fish     12/11/17

Hello Bob,
Thank you again for your advise.
I will try the Chemi-Pure and a more regular cleaning of the filter.
So many people tell you different things, for me it's very confusing.
<Mmm; don't allow it to be. SEEK to understand the underlying science; question opinions>
I will let you know the results. Until then Merry Xmas & Happy New Year Bob.
<And you and yours. BobF>
Kind Regards
Re: Black Ghost Knife fish      1/24/18

G'day Bob,
Just giving you a little feed back about my aquarium as I said I would.
<Ah, thank you>
While waiting for the delivery of the Chemi-Pure I ordered online I shopped around looking for it.
One aquarium shop had a big sale on De-Nitrate and told me it would do the job. So I cleaned the filter, added De-Nitrate to the filter, made a small water change, left the aquarium to settle tested the water.
Ammonia reading = Perfect. Nitrate = SKY HIGH, so I'm thinking you rip off barstaaards.
Chemi-Pure arrives, clean the filter add the Chemi-Pure & leave in the De-nitrate, do another small water change, after a couple of days, Ammonia reading = Perfect. Nitrate = right up there again. So then I take everything
out of the tank, flush it all clean, find buffalo head cichlid eggs in one rock in their area, take out nearly all the water vacuum the substrate , put the tank back together leave it to settle, Ammonia reading = Perfect.
Nitrate = same - NO change high as a kite. THOUGHT BUGGA THIS, took a water sample to a pet store, they tested it for me, guess what? Every thing Ammonia, PH, Nitrate and a fourth thing (can't remember) PERFECT, SHOCKED AND STUNNED, obviously I have a faulty Nitrate kit, although it doesn't expire until 2020. Get this the wife says told ya so..
<Ahh, good that you checked the checker>
All that worry, money wasted, time spent goggling and seeking advise all for nothing, so obviously the Black Ghost Knife fish and a Peacock Cichlid both died (a couple of months apart) with swollen bellies had a Parasite or something happening.
Anyway the aquarium is crystal clear like the fish are suspended in air, I'm a lot more satisfied, I have left the filter media as is:- sponges and wool in the bottom basket, then the Marine home bio balls with De-nitrate in the next basket, then the Bio-home filter media mixed with De-nitrate, in the top basket is the Chemi-Pure also mixed with the De-nitrate, there was a lot it and I still have one bag of it unopened.
<Good; best to rotate one unit out (the older) and replace it w/ new every month or so>
Now I will leave the filter alone for awhile, but I will order some more Chemi-pure ready for when the current lot expires. Eventually the De-nitrate will expire as well.
Have a good one Bob and many thanks.
<Cheers Gavin. Bob Fenner>

Water testing... NO3... SW?   2/15/10
Hi crew,
<Hi Pat>
I've been testing for nitrates with API drops, and they show "0" nitrates.
<NO3? Not likely>
I bought 6 way test strips by Jungle Laboratories, and they registered a solid 40 ppm mg/L
Water for both tests was sampled from same location in the tank.
Your thoughts please
<A dodgy test kit. Have you checked the expiry date? Try Salifert for a better, more reliable kit>

Re: Water testing  2/16/10
I failed to mention that this is a freshwater tank. Will this test kit work with freshwater?
<Should do. If in doubt, consult with the manufacturer. Cheers, Neale.>

Molly Crossbreeds and susceptibility to white spot    1/5/07 Hello from the middle of the UK <And hello from Chicagoland, Illinois, USA!> Firstly, your site really is a fantastic resource, many thanks for the hard work you must all put into it. <On behalf of the WWM Crew, thanks for the kind words.> I have found different websites have slightly varying opinions on the finer points of keeping tropical fish... <...there really are lots of views out there.  Of course, there are some concrete basics that cannot/should not be varied, but many things are debatable...lots of differences of opinion, even amongst crew members at times...> ...your site deals with this so well as the answers in the FAQs come from different people as do the questions, it's very informative, thanks again. <Glad you find it useful! I am always looking things up on the site - it's how I've learned much of what I know about the hobby.> Having prostrated myself at your feet and declared myself "not worthy" :-)..... <Well, you don't have to go that far!! lol...> I have a 150 gal tank with 2 female Bettas, 1 Plec, 1 Algae eater (long thin light orange sucky fish, not sure what to call it really)... <another type of Pleco, perhaps? Any pictures for identification?> ...7 tetras of varying types, 1 Lyre tail molly and 12 fish that came out of the Molly, I think they may be crossed with a Guppy we have in our other tank... <crossbreeding between livebearers can, and does, indeed happen> ...(we moved her and some of the offspring, she is getting quite big and the kids were taking over the tank). <Yup, livebearers can/will do that! I'm amazed they haven't taken over the planet with their reproduction rate...> Water is at 28.3 deg C +/- .2... <This is the high-side of OK for most tropical fish, but good for the Bettas...> ...ammonia 0, nitrite 0, nitrate around 40ppm... <MUST reduce the nitrate levels...20 ppm is as high as they should be.> (most of the time) ph 7.8 constant. Filter is an Atman 882, it's an in tank filter, housing a heater, 2 compartments holding bags of different filter medium and a pump, in that order as the water flows through. I do a 10% water change/clean every week and add a little stress coat type treatment (Nutrafin AquaPlus) each time to the fresh water to remove the chlorine and help the fish, I normally age the new water for 24 hrs before doing the change and add a little AquaPlus (20ml) to the tank. <Your water change schedule generally sounds OK, but since those nitrates are so high, I would recommend doing a 10% change 2 times per week, until the levels fall under control.  They really are too high and are likely stressing the fish, causing them to be more susceptible to disease.> The water from my tap is quite high in nitrate (around 40ppm) so 1 of the bags in the filter contains "Nitrate Sponge" to help keep the nitrate at an acceptable level. <Well, there's the problem, then...if you keep doing water changes with this water, the nitrate levels likely won't drop.  I'd recommend looking into a RO/DI unit, or at the very least, a DI product such as this one: http://www.aquatichouse.com/WaterPurifiers/tapwaterfilter.asp The RO/DI unit will cost you more, but will save you money in the long run, as the filters don't have to be replaced nearly as frequently as the Aquarium Pharmaceuticals Tap Water Filter product.  I don't know if they'll ship to the UK, but I am a big fan of www.airwaterice.com for RO/DI units. I'm not familiar with the "nitrate sponge" product you refer to, but it clearly isn't working.  I really suggest a water filtration system.  Everything else you describe seems great.> Questions: Can a Molly cross breed with a Guppy? <Yes.> The offspring certainly look like that is the case though there was also a male Swordtail in the other tank when she gave birth (She has also had normal Molly babies before and after this bunch arrived). <From my understanding, all livebearers are capable of cross-breeding. Might want to consider just housing a single sex, if you want to keep all these different species.> A quick aside here, she also gave birth to a Platy! <Without a platy parent?!> And we don't have any, well we do now! <OK- I'm confused a little about that one...> Why are these cross breeds so susceptible to whitespot (The pure Molly is fine as are the rest of the fish)? <I am by no means a geneticist, but my general understanding is that too much genetic variation causes all sorts of problems, including a weakened immune system.> If the nitrate level climbs above 50ppm they start breaking out with it,... <Nitrates really need to be between 0 and 20 ppm...> ...which is fine when I spend a lot of time watching them as I see the first spots and drop in some of the stress coat stuff and check the nitrate levels straight away and the whitespot goes in a day or 2. HOWEVER, if it's Christmas and I don't pay enough attention, they get in a hell of a mess in a very short time and it's out with the blue stuff (Waterlife Protozin) to fix them. <Do read here for some helpful information on treating ich.  Keep in mind that the ich parasite goes through various life-stages, and truly the only way to get rid of it is to run the affected tank fallow for at least a month... http://www.wetwebmedia.com/FWSubWebIndex/fwich.htm > Probably worth mentioning the fish in question are now at least 4 months old, maybe more.> Any ideas? The best I can come up with is that it's a genetic failing, but I wanted to check it's not something I am doing wrong, I'm not sure they like it! <It is likely a genetic weakening, and these fish will likely always be more susceptible to disease than their "purebred" parents.  The one thing you can do is to lower your nitrate levels - that's about the only problem I can see.> Many thanks again John <You're welcome. Get rid of those nitrates and you're fish you all likely be more healthy.  Best of luck, Jorie Re: Molly Crossbreeds and susceptibility to white spot (Now about Nitrate levels)  1/5/07 Hi, have replied with the previous message and comments below so you know what's going on. <OK, sure!> Firstly thanks for the info, a brief overview of your reply would be that I need to get my nitrate levels down. Great, I have something to do that should fix the problem so... 3 reasons for my reply: 1) Many many thanks to you all 2) Discussing reason 3 may help others with their searches when this message goes into the site 3) I'll be as brief as I can....... <(1) thank you,(2) this will be posted on our FAQs, and hopefully others can benefit from the info. also, and (3), no worries - I can be long-winded myself!> Up until now all the information I have read and been to me given about nitrate levels has been that they don't matter too much, and yet "Graham T" says 20ppm Nitrate is good, any more is bad, 60ppm a big no no... <Graham is one of my fellow volunteers; for some reason, I think his name got attached to our general "crew" e-mail box.  In any case, my humble understanding of water chemistry is that 20 ppm is not "good", per se, but on the high-end of acceptable.  In an ideal world, nitrates would be at zero, but that's pretty hard to achieve in reality. If the reading is 20 ppm, I do a water change, but I understand that in your case, since your tap water is coming out at 40 ppm, this really won't help.> ...and yet when I ran up my first tank a year and a half ago, I took a sample of water from the newly cycled tank to my local shop and they tested the water and did not comment on the nitrate being around 50ppm. <This is precisely why I test my own water and do independent research.  I can't tell you why your fish store wouldn't advise you the same way, all I can say is that my own readings, research and experience have all led me to the conclusion that FW nitrates must be 20 ppm or less for the ultimate good-health of the livestock.> The water from my tap has a nitrate level of 40ppm!!! <I remember - I was shocked when I first read that!> so my frequent water changes are just making matters worse. <Well, I wouldn't say worse, but it certainly explains why your last reading was 40 ppm...> I shall put my hand in my pocket and buy a water purifier. <Reverse osmosis/de-ionizing units can be expensive, but well worth it, in my opinion.  We had a problem with high phosphates in our tap water, which is what led us to purchase ours...our fish have never been healthier.  Plus, there's a drinking water switch, so you may be able to benefit from that, personally, as well!> But, a couple of questions: A quick search of WWM shows that you all think that nitrate levels are important, how come I had so much info that said otherwise? <"So much" contrary info., or just what your local fish store folks told you? Again, I certainly can't comment on why others say what they do, but I can tell you that most, if not all, reputable research in the hobby shows that nitrates, while not as toxic as nitrites and ammonia to fish, certainly aren't good and should be as low as possible...> I am beginning to thing my beautiful male Betta died because of the high nitrate levels, I won't replace him until I have got the nitrate down, he was more of a pet that a pretty fish in a tank, real personality, sob sob etc... <I agree with you - I've got three Bettas (two males and one female, all separate, of course), and they are my favorite fish.  So much personality, and beautiful, as well.  I can't say that the nitrates killed your Betta, but they surely didn't help.  Another common problem with folks keeping Bettas is not keeping them in a min. 2-3 gal. filtered tank, with a heater set to a constant 80-82 degrees F...I'm sorry you lost your little friend.  Once you get your RO/DI unit, and a suitable tank for the Betta, you will be all set, as they are very low maintenance once these general requirements are met...> sorry, had to let it out somewhere :-) best to do it where I maybe understood. <Ask my boyfriend - I am the nutso-save-all-the-Bettas-in-little-cups-in-PetSmart lady - I'm in the process of writing a simple how-to-care-for-your-Betta article.  It's one of my passions! Long life the Bettas...I can keep going for ever:-) > Second and maybe even more importantly, myself and my family (and everyone else in the town) are drinking tap water with a nitrate level that makes fish ill. Is this bad for humans?????? <Well, I'm not a doctor, but I can't imagine it's good.  Again, if you invest in a RO/DI unit, I would look into the drinking water attachment...> Finally a note for the Google search to help others... " High nitrate levels in tap water " :-) <Thanks - will pass this along.> My complete thanks to you all John <You're welcome, John.  And, your P.S. re: a FAQ on sending pictures - I am forwarding that along to Bob Fenner himself.  I'll happily admit I am not a computer junkie, and as this is Bob's site, he's the best one to help you out on that note. I'm sure he'll appreciate the advice/suggestion.  Best regards, Jorie>

No Nitrates  - 01/09/2006 Hello I have 4 tanks that have been running 6 months +.  I was wondering when I tested the water I have as follows: 0 ammonia,0 nitrites and 0 nitrates.   I have contacted the test company and they ensure that the test was produced in may of last year so that it is unlikely that the test has gone bad. I was wondering if I should worry about this or just consider myself lucky that I have good tanks.  I have had several fry, my fish all seem very healthy, and their coloring it good. Thanks for any info. Jill < Plants and algae will remove nitrates. Get a water sample from one of the tanks at your local fish store. If it still reads zero then I would change kits and get one with a powder reagent instead of a liquid reagent.-Chuck>

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