# What level of nitrates indicates problem overstocking?



## Cich of it all

*At what nitrate level should a tank's stocking level be reduced or water changes be done more frequnetly?*​
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## Cich of it all

Somebody in another thread told me that if nitrate levels in a tank exceed 20 ppm, the tank's stocking level should be reduced or water changes should be larger or more frequent. I've gathered from experience and what I've thought to be the general concensus that something more like 80 ppm is a more reasonable "redline" when it comes to high nitrate levels being a major problem. Assuming the fish are not overfed, what do you all think?


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## Guest

I've heard nitrate levels under 30ppm are safest long term *but* under 20ppm is more ideal.

Someone who knows more about this/more experience let me know if I am wrong!

~Ed


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## Number6

I saw that part of the other thread, and I was very interested... back in the day when I knew less about maintenance than I do now, one Malawi mbuna tank had a nitrate level of over 120ppm (old test kit read lower, new one read at that!  ) ... no fish died, but I did step up the water changes when I saw that and brought it back down to the 40 or so ppm level...

So the issue with Nitrate is certainly not black and white.

I also setup a Walstad no water change planted tank once... I found (even with nitrate at below 10ppm) that the TDS crept up over time, and fish started showing mild unhappy signs until I gave in and did a water change... then all was good for another 3 to 6 months...

So is it just the nitrate that is the problem? or is nitrate simply an indicator of when all pollutants from fish have built up to problem level?

Has anyone added nitrate to a tank of fish and tested "just" nitrate in a tank of cichlids?

I searched once for published papers on NitrAte and toxicity to fish... never found one. Plenty on nitrite, ammonia, etc.

I've basically come to the conclusion that high nitrates are bad... but how high is bad? I don't think we know... pity!


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## Shwaine

Think of nitrates like the aquarium equivalent of dust in a house. It's an easy to read indicator of when wastes have built up and it's time to clean. Since nitrates are produced directly from the conversion of ammonia in fish waste, then there is a direct relationship between waste production and nitrate levels. Letting nitrates build up will let all the unmeasurable wastes also build up. In the case of the Walstad system, you removed your primary indicator without handling all waste products.

Fish tanks are just too small to have an entirely closed ecosystem. There will either be a build up of some products or an exhaustion of vital nutrients. Both of these are counterproductive to long-term health. Water changes remove the waste and restore the vital nutrients. Nitrate level is the best indicator we can get with our home water test kits of when the tank is degrading and needs another water change. And if nitrates are kept under 20ppm, you can be pretty sure you're doing all humanly possible to remove the waste products and restore the vital nutrients. It's just like cleaning the house when you see some dust laying about.


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## Cich of it all

Please understand the topic here. I'm not asking what ideal nitrate levels are as that is simple common sense. Obviously the lower the better. Zero , although nearly impossible without plants, would be the best. What is being asked here is: 
_"At what nitrate level should a tank's stocking level be reduced or water changes be done more frequnetly?"_ - as in when are nitrate levels so high that they can adversely affect the fish. 
I would really like this poll to indicate that, and not just what people think of as "best" or what their tank's nitrate levels actually are. I don't believe that a small amount of dust in the air in my house is going to be harmful to me, but visible clouds of it are probably going to make me cough and trigger allergy symptoms. My tanks never exceed 50ppm, and that's just an estimate since the API color card goes from 40 to 60. (My results never look too much more red than the 40ppm color.)


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## pugwash

This might make an interesting read, although couldn't find the paper it refers too.

http://www.practicalfishkeeping.co.uk/pfk/pages/item.php?news=560

Edit: found it but refuse to pay for download. Here's the abstract though:

Published data on nitrate () toxicity to freshwater and marine animals are reviewed. New data on nitrate toxicity to the freshwater invertebrates Eulimnogammarus toletanus, Echinogammarus echinosetosus and Hydropsyche exocellata are also presented. The main toxic action of nitrate is due to the conversion of oxygen-carrying pigments to forms that are incapable of carrying oxygen. Nitrate toxicity to aquatic animals increases with increasing nitrate concentrations and exposure times. In contrast, nitrate toxicity may decrease with increasing body size, water salinity, and environmental adaptation. Freshwater animals appear to be more sensitive to nitrate than marine animals. A nitrate concentration of 10 mg NO3-N/l (USA federal maximum level for drinking water) can adversely affect, at least during long-term exposures, freshwater invertebrates (E. toletanus, E. echinosetosus, Cheumatopsyche pettiti, Hydropsyche occidentalis), fishes (Oncorhynchus mykiss, Oncorhynchus tshawytscha, Salmo clarki), and amphibians (Pseudacris triseriata, Rana pipiens, Rana temporaria, Bufo bufo). Safe levels below this nitrate concentration are recommended to protect sensitive freshwater animals from nitrate pollution. Furthermore, a maximum level of 2 mg NO3-N/l would be appropriate for protecting the most sensitive freshwater species. In the case of marine animals, a maximum level of 20 mg NO3-N/l may in general be acceptable. However, early developmental stages of some marine invertebrates, that are well adapted to low nitrate concentrations, may be so susceptible to nitrate as sensitive freshwater invertebrates.


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## Cich of it all

From that article:


> "Just 10ppm of nitrate-nitrogen (that's a mere 3.03 ppm of nitrate) has been shown to have adverse effects on salmonids such as Oncorhynchus mykiss, Oncorhynchus tshawytscha and Salmo clarki, as well as upon a number of freshwater invertebrates and frogs."


Boy that's almost saying that keeping *any* fish in an aquarium is cruel.


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## Cich of it all

Please post the link to the article. I may just break down and pay for it.


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## pugwash

Cich of it all said:


> Please post the link to the article. I may just break down and pay for it.


Lol.. here you go.

[/url]http://www.sciencedirect.com/science?_ob=ArticleURL&_udi=B6V74-4F02KWG-B&_user=10&_coverDate=03%2F01%2F2005&_rdoc=1&_fmt=&_orig=search&_sort=d&view=c&_acct=C000050221&_version=1&_urlVersion=0&_userid=10&md5=9223511f8116baa0afab922feac45ee9[/url]


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## Cich of it all

Hmm. Well $30 is a liitle pricey. It looks like the article and data are focused mainly on invertibrates, which are more sensitive to nitrates.


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## chapman76

I've always worked under the assumption that anything under 40ppm is fine. Mine normally never go above 30ppm, but if I'm feeling last, I know I have another few days to get around to it.


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## Number6

you guys need to get better at Google 

i found the article online...

it appears that the effect of nitrate depends on age of fish and species... to be expected.

"Knepp and Arkin (1973) reported that the channel
catfish Ictalurus punctatus was able to tolerate a nitrate
concentration of 90 mg NO3-N/l without affecting their
growth and feeding activity after an exposure of 164
days"

"The first indication that relatively low concentrations
of nitrate might be harmful to fish came from Grabda
et al. (1974). They reported that fry of rainbow trout, exposed
to 5â€"6 mg NO3-N/l for several days, displayed increased
blood levels of ferrihemoglobin, alterations in
the peripheral blood and hematopoietic centres, and
liver damage."

The interesting thing is that the fry were sensitive to such low concentrations...

Keep those fry tanks spotless folks!


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## spqrzilla

I would expect trout species to be among the more sensitive of vertebrate freshwater fishes.


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## Cich of it all

This is getting scary! Even my lightly stocked tanks exceed 30 ppm!
Any suggestions for lowering nitrates other than larger / more frequent WC's or a reduction in stock? 
Chemical filter media? 
Planted refugium?
In-tank plants that Mbuna won't eat? (what are some? Vals? Java fern?)


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## Number6

I would suggest that in high nitrate containing source water, one should take care to keep the water on the cooler side and to really aerate the water. 
The other things to do would be to use floating nitrate sucking elodea, hornwort etc. in a sump tank. 
Of course, the difficulty of plants as a tool for keeping nitrate low is that you have to monitor the plants for any rot or the rotting leaves can dump the nitrate back in.

All floating plants should be harvested often and any older looking stems/ leaves need to be pulled out frequently.


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## NorthShore

I'm not sure why feeding and food has been left out of this equation when I think it is the most critical piece. Nitrate levels can be drastically affected by overfeeding and using foods that are not properly digested by the fish and excreted as ammonia. So conversely, feeding only what is truly required and using a highly digestible food would lead to a lower nitrate readng.

Having said that, I try to keep my tanks below 20ppm. I usually do 50% water changes weekly and this seems to keep them way down.


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## Cich of it all

I bought a different test kit today. I was using API, not I'm going to try Sera. I'm told they are the best, but you pay for it!


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## eric

I enjoyed reading this post, intelligent conversation by all.

I don't think that I can answer the orginal question, as I'm not a chemist. Maybe the person who told you about keepng your levels below 20ppm is. I use the powers of observation in order to understand what I should be doing in terms of nitrate reduction.

I also ran a heavily planted tank that utilized metal halide lighting and CO2 injection. Nitrate levels were zero every time I tested, no matter when I tested. Did the tank benefit from water changes? You bet it did! Every two weeks I did a 20% water change and the differences were obvious. The plants would go into serious photosynthesis. Anywhere a plant was torn, a stream of oxygen bubbles rising through the tank resulted. In addition, the fish became more active. It was a day and night difference.

It goes back to some of the earlier replies. You can't measure the dissolved organic compounds (DOC's) in the water which have a detrimental affect on the fish. Nitrates are just one of the bad guys and they are easy to measure. Can they be used as an indicator of water quality in the aquarium? Sure. But please consider that there are so many things going on in the aquarium that even noted authorities will tell you they don't have all the answers.

If you poll question had the answer "Forget focusing so much on nitrate levels and just watch the fish", I would have checked that one.


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## Cich of it all

> If you poll question had the answer "Forget focusing so much on nitrate levels and just watch the fish", I would have checked that one.


 :lol: 
I just want to make sure that I'm doing the best I can to provide the most humane conditions possible for my fish. I love 'em in nearly the same way I do my cat and dogs, so I want them to live as long as possible without any adverse affects due to my negligence. 

For the sake of my water bill, I don't want to have to do more than one 50% WC per week. I am quite satisfied with my current communities though. Maybe the new test kit I bought will show less nitrates than my old test. (although it really isn't that old - 6 months - it showed as much as 50 ppm, which because of this thread, I'm now finding to be too high.) I'll find that out tonight. If I am still getting 50 ppm, I will increase my weekly WC's to 50% (from 35-40%), and maybe reduce the stocking levels a bit. I'd prefer to stay away from the latter though, because like I said, the current mixes are working very well.


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## pugwash

Number6 said:


> I would suggest that in high nitrate containing source water...other things to do would be to use floating nitrate sucking elodea, hornwort.





eric said:


> Did the tank benefit from water changes? You bet it did! Every two weeks I did a 20% water change and the differences were obvious. The plants would go into serious photosynthesis...the fish became more active. It was a day and night difference...If your poll question had the answer "Forget focusing so much on nitrate levels and just watch the fish", I would have checked that one.


My tapwater has nitrates of 50ppm, comfirmed by my water dept and testkit. Sadly, the legal limit in London (UK) is 50ppm! My tank runs at 20ppm, through simple, yet effective means.

A bunch of hornwort which regularly needs trimming as Number6 says, but with the added chemical filtration of Seachem's Purigen in each filter (a nitrate absorbing polyresin recharged by bleach); this maintain's the tank at 20 ppm. But as eric says the DOC's accumilate, and only PWC's (20% in my case) can counteract this resulting in more active fish on all accounts! The nitrates may briefly rise, but the filtration sorts this out (with monthly or so recharging of each resin pad on a monthly cycle). My sultry FM a shown new colours and behaviour since I followed this regime, and my growing EBJD is showing new colours! :thumb:

Adaption is our greatest key!


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## 24Tropheus

Just to make you feel all the more guilty nitrate levels in real Lake Tang water are below measurable levels  but in some other waters far higher than 100. I guess it depends on the fish you are keeping. Sorry but my tank nitrate level is below 5 and I still do 50% water changes with tap water that reads 5. I still can not figure out why this works.


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## Big Vine

Please consult the following article:
http://www.oscarfish.com/index.php?page ... rticle&k=7



pugwash said:


> My tapwater has nitrates of 50ppm, comfirmed by my water dept and testkit.


Ugh, sorry to hear that.  
I'll quit complaining about my tapwater's 5*.*0 PPM level of nitrAtes. :wink:

BV


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## prov356

Good link, BV. Based on that and to answer the op, I'd suggest striving for below 10, and 20 indicates a need for a water change. If that becomes impossible to do, 
then I'd say it's time to review stocking, feeding, filtration, and maintenance. Like the article, I liken nitrate exposure to long term exposure to cigarette smoke. 
It's a long term detriment to health. it may exhibit itself in shortened lives of the fish. That may be the cause of many a fish death, but it's hard to detect because the 
fish lived for 4-5 years. At lower nitrate levels, it may have lived a few more years. Kind of like the difference between living in a house of smokers vs a smoke free environment.

The way I've found to keep nitrates down is to keep the organic load in the system down.

Use filters that lend themselves to frequent and easy cleaning and clean often, at least once per week.

Vacuum substrate at least once per month, twice is better, and move those rocks and get under them too

Feed a nutritious food and don't overfeed

Identify every area of the system where detritus may accumulate and work the removal of it into your maintenance routine. For instance, the mulm that can build up in the bottom of a sump.

Following the above, I've kept my nitrates down to around 5ppm with only 25% weekly water changes. It hasn't budged off of that for a long time. I've never seen it over 10. 
I also use Purigen, but I'm not sure how much that helps. Plants consist of a few java fern and they've had no effect. It's not the plants. Plants may help, but shouldn't be looked on as the solution.

Nitrates are the end product of the nitrogen cycle and what feeds the cycle are organics. Starve the cycle.


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## Cich of it all

This is all very discouraging. Hereâ€™s one example why:
In my 90 gallon, which is probably more like 65 gallons once you figure in the rock, substrate, and the â€œactualâ€


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## eric

prov356 said:


> The way I've found to keep nitrates down is to keep the organic load in the system down.
> 
> Use filters that lend themselves to frequent and easy cleaning and clean often, at least once per week.
> 
> Vacuum substrate at least once per month, twice is better, and move those rocks and get under them too
> 
> Feed a nutritious food and don't overfeed
> 
> Identify every area of the system where detritus may accumulate and work the removal of it into your maintenance routine. For instance, the mulm that can build up in the bottom of a sump.


Great advice!

With an emphasis on the filter. After all, what is producing the nitrates and where are much of them stored?


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## Paul_DLS

I've always appreciated the deep aquifer the local water is drawn from, but after reading this topic and having a look at the sites below this is the first time I've appreciated all the clay that protects it. Just got a nitrate test kit: Tap = no measurable ppm, Tank = no measurable ppm. Instructions were well followed and test repeated three times.

NSGS Nitrate Ground Water Contamination Info: http://water.usgs.gov/nawqa/wcp/
NSGS Contamination Risk Map: http://water.usgs.gov/nawqa/wcp/wcpfig1.html


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## prov356

Paul_DLS said:


> I've always appreciated the deep aquifer the local water is drawn from, but after reading this topic and having a look at the sites below this is the first time I've appreciated all the clay that protects it. Just got a nitrate test kit: Tap = no measurable ppm, Tank = no measurable ppm. Instructions were well followed and test repeated three times.
> 
> NSGS Nitrate Ground Water Contamination Info: http://water.usgs.gov/nawqa/wcp/
> NSGS Contamination Risk Map: http://water.usgs.gov/nawqa/wcp/wcpfig1.html


What's the history on the tank and what do you attribute 0 nitrates to?


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## Paul_DLS

Tank has been setup in its current state for several months. Tank water changes were recently stepped up to 20% weekly as a precautionary measure since some fish were showing signs of parasite infection and I had not been bothering to check nitrates (believed previous sched. of 10% changes per week was adequate). Tests were performed 5 days after a 20% change and before a 25% water change and the introduction of meds. to the tank.

Due to the low starting level of nitrates in my tap water I am considering returning to the old schedule of 10% changes.

9 - yellow labs (adults w/ one holding) had 2 yrs and many gens.
5 - rusty juvs added 2 wks ago
5 - acei juvs (added one of these guys yesterday, rest 2wks back)
3 - syno. petricola juvs added 2 wks ago
1 - Borlei added 2 wks ago
1 - 7.5" comm. pleco


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## Cich of it all

Is this the 55 gallon you have listed in your sig? If so I don't see any plants in that tank, and that's about the only way you could have zero measurable nitrates. I see you have a prettty heavily stocked tank, and many of the fish were added within the last 2 weeks. How are your ammonia and nitrite levels?


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## prov356

Which kit are you using? Low nitrates in source water isn't unusual in the US. 0 nitrates in a several month old tank with only 20% weekly changes and no other means of nitrate reduction is pretty much unheard of. I think I'd get hold of another kit and test again.


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## Cich of it all

I could believe the unmeasurable nitrates in the water, but if the kit is not bad and you have no nitrates in the tank, you may have disrupted the cycle with the addition of those newer fish. Is the penguin 330 the only filtration that you have?


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## Paul_DLS

No ammonia per API test kit & Seachem Ammonia Alert (2 wks old).
No Nitrite per API test kit.
Nitrate test kit is API and brand new.

I have not updated my tank info in the last several months.
Filtration is a Magnum 220? H.O.T. canister & an in-tank hodgepodge of DiY.
My DiY background cuts off a corner of the tank for the USJ pump, heater, a tall bag of argonite with imbedded airstone, 15 pot scrubbers w/ airstone underneath them, and occasionally a sm. bag of carbon (not now due to meds.).

Scrubbers & argonite removed:









Scrubbers & argonite in:









Large view of scrubbers & argonite bag temp. in front of BG:
http://i186.photobucket.com/albums/x278 ... P_1846.jpg

I've since painted a black strip over the division of life support corner(LSC) & housing. Now I need a bit of something removable to cover LSC, then build a canopy ...


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## Shwaine

Shake the second reagent bottle of the API nitrate test kit thoroughly (ie if you think you've shook it enough, shake it again for another minute for good measure). That one seems prone to seperating and giving false 0ppm readings. Just because the kit is new to you doesn't mean it hasn't been sitting around the retailer's shelf long enough for the reagents to settle. I personally prefer the dip sticks for nitrate tests just because it removes user error from the equation and one does not need absolute precision for nitrate testing.

Now there are ways for nitrate to be removed from the tank without water changes, so that could be happening too. The major pathways are plant metabolism, nitrate absorbing resins (tend to only remove small amounts though), ammonia removal via resins or zeolite (so the tank doesn't cycle since there's not enough ammonia to feed the bacteria), low pH (converts ammonia to ammonium and inhibits the cycle bacteria) and anaerobic bacteria (converts nitrate to nitrogen gas, usually results from a thick, undisturbed substrate).


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## prov356

Shwaine said:


> Shake the second reagent bottle of the API nitrate test kit thoroughly (ie if you think you've shook it enough, shake it again for another minute for good measure). That one seems prone to seperating and giving false 0ppm readings. Just because the kit is new to you doesn't mean it hasn't been sitting around the retailer's shelf long enough for the reagents to settle. I personally prefer the dip sticks for nitrate tests just because it removes user error from the equation and one does not need absolute precision for nitrate testing.
> 
> Now there are ways for nitrate to be removed from the tank without water changes, so that could be happening too. The major pathways are plant metabolism, nitrate absorbing resins (tend to only remove small amounts though), ammonia removal via resins or zeolite (so the tank doesn't cycle since there's not enough ammonia to feed the bacteria), low pH (converts ammonia to ammonium and inhibits the cycle bacteria) and anaerobic bacteria (converts nitrate to nitrogen gas, usually results from a thick, undisturbed substrate).


That's what I'm looking for as well. Unless there's some means of nitrate removal as mentioned, or it's not being produced in the first place, it can't be zero. if the nitrogen cycle is running, it's being produced. If there's nothing in the system or system maintenance (100% water changes) to remove it, it's got to be there. Starting with 0 nitrate source water won't achieve 0 in the tank. I'd also suggest trying a new kit, different type. Instant Ocean dry reagent kit is another possibility.


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## Paul_DLS

The bottles are dated 2006.
I took the bottles (solutions 1 & 2) and set them in warm water for 15 mins.
I then beat the bottom of solution 2 against the counter for 1 min.
I took both bottles and strapped them to the blade of a saws-all and ran the saw for 3 mins.
(The motion of a saws-all or reciprocating saw is a rapid back and forth movement.)
I then followed the instructions including all additional mixing and shaking required as I had before.

Tap = 0
Tank = 40ppm using freshwater chart/ 80 if I go by the salt water

I appreciate the persistence of several members.

Since I have less than 5 TBSP Epsom & 5 tsp sodium chloride in the tank and a marine tank would take over 14 lbs for a 55g I figure I should be going by the freshwater reading unless the presence of ANY salt alters the test rather then the amount of salt.

The 40 ppm is concerning since I did a 25% water change 40 hrs ago. I've got another change due tonight before doing the 2nd of 3 parasite treatments. The good news is that I have a lot of bacteria doing work in there. I have some testing and adjusting to do in the next few weeks to come up with a healthy and economical water change schedule.


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## Number6

Paul_DLS said:


> I took both bottles and strapped them to the blade of a saws-all and ran the saw for 3 mins.


 Genius! I love it... will remember that trick...



Paul_DLS said:


> The 40 ppm is concerning since I did a 25% water change 40 hrs ago.


high nitrates for a prolonged period of time can increase the chances of an opportunistic disease. 
I'd assume that the 40ppm is accurate. This can be checked by immediately doing a 50% water change which will help the sick fish as well as remove half the pollution. Test should now read at or very close to 20ppm if all is working right.

Your experiences with the test kit will make for a good reference for people who think they have 0 nitrate in a fully cycled and running tank. Thanks...


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## jrh

So if I'm showing <5 nitrates in a 12 gallon, moderately planted, with 6 multis and 1 small ancistrus, and some MTS, should I be skeptical about the test results?

I add the drops from the first bottle, shake. Shake the 2nd bottle, add drops, shake, and wait.

There's dense fern in the back, light fern in the midground (pictured), some moss in the foreground.


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## prov356

> should I be skeptical about the test results?


I'd say no for a few reasons. First one, you are getting a reading. Usually when the test isn't done right, you get a zero reading. You also have a fairly lightly stocked, moderately planted tank. With good maintenance (keep organics down), moderate stocking and feeding and regular water changes, 5ppm is very doable. I've got a 180 that stays under 10. Lightly planted (meaning a few java fern). Confirmed with different test kits over a period of time. Can be done.


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## jrh

prov356 said:


> should I be skeptical about the test results?
> 
> 
> 
> I'd say no for a few reasons.
Click to expand...

Thanks. Everything seemed to be going well, but I haven't kept a tank in 15 yrs, and we certainly didn't do all this testing back then.


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