KNO3 readings what is average?

1077

Guru Class Expert
Aug 19, 2010
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Am wondering at what levels are NitrAtes a concern for those with plants/fish?
Judging from readings I have been measuring with API test and fish load in my low tech low maint 80 gallon tank, I can't help but be a bit concerned at 80ppm readings with 1/4 tsp KNO3 every other week and once a day feedings.
Have resisted the urge to perform water change in non CO2 tank and am simply reducing the amount of KNO3 I am adding but an curious as to what readings or levels do others see as normal or abnormal?
My fishes exhibit no signs of discomfort or abnormal behaivor and plants are doing well, just wondering what those who are more expierienced think?
Have never run a tank with NitrAtes over 20 ppm and would welcome thoughts or opinions . Thanks in advance, Lee.

P.S. should I even be relying on the results from API test ?
 

dutchy

Plant Guru Team
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Jul 6, 2009
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Nitrates are not toxic to fish and most certainly not to plants even in high concentrations.

In a non-CO2 tank without waterchanges and with moderate biomass you could go as low as dosing 1 ppm per day. Some tanks even have a "balance" where actually the food and other waste is enough to provide in NO3. If you don't want to do a waterchange, just stop dosing for a while until you measure more "normal" levels.

I usually have a NO3 level that fluctuates between 20 and 40 ppm.

To rely on a test is a big word, but it can give you some indication though.

regards,
dutchy
 

1077

Guru Class Expert
Aug 19, 2010
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Thanks for the quick response.
I think I'll just stop with the KNO3 for a couple weeks, and try and determine at what rate the plants can lower /use up what is there.
'Have read numerous studies that suggest that Nitrate levels much higher than what I normally try to run are not harmful ,at least with some species of game fish ,but I have had better than fair results with lower levels as opposed to higher in non planted tanks.(Dwarf cichlids,Discus,South american cichlids)
This is new for me (plants in substrate) as opposed to a few potted plants ,and I am pleased with the fishes apparent pleasure with the plants just don't want to fix somethin that ain't broke yet nor do I wish to encourage problems.
Again Thank you .

Regards,Lee
 

1077

Guru Class Expert
Aug 19, 2010
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Well after a couple of weeks, of no KNO3 and 50 percent water change, Nitrate levels according to API test kit still indicated 80ppm. I pitched the test Kit and will watch the plant's/fish and resume the 1/4 TSP of KNO3 per week or every two weeks.
I hoped the lack of dosing KNO3 for a couple weeks would lower the readings and when this did not happen,I performed 50 percent water change and tested an hour later, and results were same.
In my mind, the test kit was expired so I binned it.
I could understand if previous dosing had not been used by plant's and thus readings were same, but after 50 percent water change,readings should have dropped hence my belief that the test kit was faulty/;expired(Four or five years old)
As mentioned, I'm just gonna watch the fish and plant's and resume with 1/4 TSP KNO3 once a week or two for my 80 gallon tank along with 1/8 TSP Potassium which I have been maintaining.
I seldom use a test kit, but became curious as to what nitrate level's were after dosing KNO3, and two weeks of not dosing. I didn't learn much, but thankfully plant's are thriving and fishes appear to all be thriving as well.
I am thinking I will probably go with once a month water change's. I seem unable to let the tank go longer than this.If I had fewer fish,perhaps.
 

nipat

Guru Class Expert
May 23, 2009
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Can it be that your NO3 is actually about 160 PPM?
The color of 80 vs 160 is very close.

If it were me I would scoop some water from the tank
into a bucket and mix it with tap water to see.

Or use the calibration method to verify if it's still good or not.

I'm more concerned about the level because the tank is low tech style
(no water change).
 

1077

Guru Class Expert
Aug 19, 2010
189
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No, I don't believe the readings were higher as the color chart rendering for readings of 160ppm is a decidedly brown color (to these eye's) as opposed to bright red to orange for readings between 40 and 80 ppm.
Tapwater levels were first thoughts I had,and have always been non existent and test kit I tossed indicated as much.
Have not cleaned the canister filter other than quick backflush a month ago,perhaps I have a nitrAte factory there.
Some may poo poo my concern's about possible nitrAte level's and I can accept that, but for my tanks,my fish, I would prefer to keep them at level's I am comfortable with and hope that the plant's and fish continue to do well.
Too late for any more testing with the old kit for the trash man hath cometh.
I'l just have to pick up another kit.
 

fjf888

Guru Class Expert
Oct 29, 2007
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Northern Virginia
You could get a better level of comfort by calibrating your new nitrate test kit using the instructions on here. You can use your KNO3 to do it. That should give you assurance one way or the other. I remember an article or perhaps a forum post by Diana Walstad that concluded 80 ppm of KNO3 is completely benign to fish, and in fact higher levels of nitrates are fine as well. I remember their being an exception or two, such as either brook trout or brown trout, which is not surprising, but nothing regarding the types of fish we all normally keep.

Still like you, I get a little panicky if the nitrate goes above 40 ppm (Ican't help it). I have also not noticed any correlation to this or any other problems. FWIW. It may although be a good indicator on a CO2 injected tank that more CO2 needs to be added.
 

SuperColey1

Guru Class Expert
Feb 17, 2007
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I just went back to CO2 adition but prior ran it as a non CO2 tank with no water changes for a year. Only dose macros (EI mix of KNO3 and KJH2PO4) once a month or so. Just waited to see the start of GSA on the anubias as a sign to add 5ml. So 5ml every month or so for a year.

Never tested the nitrates and the fish were still very happy and breeding too much :)

AC
 

aquabillpers

Lifetime Charter Member
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I use the API nitrate test kit and I am quite happy with it. However, my eyes don't see much of a difference between 40 PPM and 80 PPM.

For what it's worth, I add 1/4 Tsp. of KNO3 about every 4 to 6 months, to a fairly heavily planted 29 gallon tank.

Bill
 

1077

Guru Class Expert
Aug 19, 2010
189
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Thank's Fred,

I shall search here for calibration instructions if for no other reason, to give me an idea of how much product I am wasting or not wasting.
I Feel I must take fish load into account ,and perhaps I don't need to dose KNO3 nearly as often.
 

1077

Guru Class Expert
Aug 19, 2010
189
2
18
SuperColey1,
Yes,I am thinking (alway's dangerous) with fish load I have, and am planning, I may not need to dose but once a month .
Have went from 3/4 tsp KNO3 in 80 gallon heavily planted, to 1/2 Tsp, to now 1/4 tsp every week or two.
Should I see any negative results in growth, I shall return to previous dose.
I really wish I had not been so inquisitive with regards to NitrAte level's ,but some habit's die hard.
 

SuperColey1

Guru Class Expert
Feb 17, 2007
503
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Lincoln, UK
Indeed. It is a recurring 'reply' to many posters on the forums when they move from non planted to planted and even many that have been planted for years. They have had 'test, test, test' driven into their mindset and they often find it hard to believe that tests can be inaccurate or that they are not needed.

As for fish load I have a breeding group of Corys (8 in all) a breeding school of Rasbora (11 adults and they eat the eggs. lol) and an uncountable colony of chery shrimp (probs around the 1000 mark no exaggeration)

That is all in a 125ltr with no problems with CO2 and dosing or without CO2 and dosing.

AC