# Optimum Nitrate Level?



## FishFarmer

Okay, so I've done some searching around here and elsewhere online and I can't seem to find a straight answer to my question. My question is, what is a good nitrate level for a planted tank with fish? Some places claim that zero is best for fish. Maybe so, but my plants wouldn't think that's so good. I've also read that most fish can tolerate VERY high nitrate levels with no adverse affects, while other sources claim that just 5ppm will cause stress.

So what is a good level? What are your nitrate readings? Right now my tank is ~20ppm nitrate, and I will be getting fish soon and I want to make sure my nitrate levels are okay.

Thanks!


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## mistergreen

Reefers keep nitrate low for their sensitive SW fishes.

That doesn't apply to FW fishes. 20ppm would be fine. Personally, my nitrate doesn't go above 10ppm and below 5ppm.


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## BlueJack

anything more than 0 :icon_smil....all your trying to do is make sure nitrogen won't be a limiting factor.


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## Jeff5614

I think it's all dependent on your tank - light levels, type of plants, etc.


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## farrenator

I regularly had nitrate levels of around 30ppm when I had a tank overstocked with rainbowfish that I over fed. The fish were never distressed, diseased etc. That may be on the high end but I never had a problem with it. The ottocinclus didn't mind either. YMMV but I wouldn't stress out about it too much.


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## lauraleellbp

There's a huge difference in overall water quality in a tank between nitrates that are a result of the accumulation of organic buildup vs. one where the nitrates are from dosed ferts.

I personally run less than 5ppm in all my own tanks- but they're also low light/low tech. If I ran a high tech tank with CO2 I'd probably shoot for around 20ppm.


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## Jeffww

I've got tanks with ppm from around 20ppm to all the way up to 80ppm. Both are high tech both get great colors and good growth. Whatever you're comfortable with...Some say fish are stressed by it. I personally see no evidence but I understand some people who see a chance in hurting an animal like that even unintentionally would avoid the risk. I personally am slowly trying to reduce the nitrates in my tanks not for my flora but for my fauna.


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## Booger

A crapton. I dose ~50ppm/week and seem to hover around 20-40. I'm not trying to breed discus or anything, though.


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## FishFarmer

Thanks for all the input everyone. It looks like it isn't something to be terribly concerned with. I think if I keep it in the 10-20ppm range I should be okay.


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## ray-the-pilot

*+1 on 10 - 20 ppm*



FishFarmer said:


> Thanks for all the input everyone. It looks like it isn't something to be terribly concerned with. I think if I keep it in the 10-20ppm range I should be okay.


After three years at 10 - 20 ppm, I'd say it is just about right. If it gets higher your plants are probably in trouble and not taking up enough NO3. Below this your plants will be in trouble.


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## flip9

I do my water changes once it hits 20ppm


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## happi

ray-the-pilot said:


> After three years at 10 - 20 ppm, I'd say it is just about right. If it gets higher your plants are probably in trouble and not taking up enough NO3. Below this your plants will be in trouble.


I disagree, plants will still take No3 even when its high, some of my plants did not show any improvement at lower levels of NO3 (10-15ppm), i went with 30ppm or higher and plant started to take off. i think some plant takes No3 better when its at higher levels.


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## plantbrain

ray-the-pilot said:


> After three years at 10 - 20 ppm, I'd say it is just about right. If it gets higher your plants are probably in trouble and not taking up enough NO3. Below this your plants will be in trouble.


I agree, except at higher levels, this is not an issue.
The plants should not be in trouble either way if the dosing is higher or not......
in other words, some other dependent factor is causing a problem, not the NO3 themselves.

The range is likely up to about 80--100 before you see a slight decline in growth(see Gerloff 1966), but then again, hydroponic solutions like modified Hoaglands are 235ppm N and mostly NO3 since NH4 will burn roots. such solutions are what are used to measure non limiting growth as well as are used for Tropica and most aquarium plant commercial growers.

http://www.new.aslo.org/lo/toc/vol_11/issue_4/0529.pdf

Gerloff and Kromboltz (Paul who still post every so often on forums) used a 1/5th dilution of the hoalglands to do this study. I see no issues, but they also did not use CO2, sediment based ferts etc and the study was for 8 weeks, not 2 years etc.....

Also, luxury uptake may not be that in natural systems which vary greatly in terms of nutrients. Times are plenty and times are lean, so unless you look at the entire seasonal cycles..........it may not show the whole story. Under horticultural conditions........perhaps, but not natural ones. 

Still, a target of 10-30ppm is what I and the group in the Bay area cam eup with about 15 years ago and it's been pretty good, some suggest 5-10ppm, eg PMDD or the plagiarized version of PMDD: PPS.

This works, but care needs to be done to ensure the testing is accurate and the dosing is consistent, light is lower etc. No reason why that cannot be done under those conditions.

Some weedy stem plants did not do so well and there was less need to maintain such lower levels at those ranges, and many never calibrated test kits for NO3, so they often bottomed out and adding a bit more buffer room seems to help that human issue. EI was a response to that issue. Made management and the likelihood of errors easier for most folks+ required less testing/expertise.


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## plantbrain

happi said:


> I disagree, plants will still take No3 even when its high, some of my plants did not show any improvement at lower levels of NO3 (10-15ppm), i went with 30ppm or higher and plant started to take off. i think some plant takes No3 better when its at higher levels.


How where those NO3's measured?
Also, which plants?

Mic umbrosum was among the 1st ones we found that did not do as well below 10ppm NO3.

If you have soil, or ADA As etc...then the water column is not the only source etc, but with plain sand, this can be done without influence from other sources etc.

I've noted smaller dia of the stem plants under stronger N and P limitation, about 30-50% smaller diameters(or leaf length's). This was for Myriophyllum matogrossense in an ADA run tank.

At 15ppm or more, they grew much larger and at a higher rate of growth(2-3x). Same for P stellata and L. cuba among others. Some folks might like the larger sizes however, some say they like the smaller more stressed look.

Bonsai also hold this view often times as well. I love me some Bonsai for a very long time. But if it's just used to justify their ego's in a debate.......well, then that's another issue. Then it's really not about aesthetics. 

I see the stunted discus folks howl over smaller fish, but in nature, they are never as big as the fat pigs we often have also, but perhaps folks want smaller fish to fit into their smaller tanks? I do not know there.......but one could make the argument.

Same for weedy species and slowing them down with less N.
I think less P would be a better idea if you wanna force CO2/light etc at higher levels, otherwise go non CO2 to slow and reduce the sizes.

Then optima might be only .5ppm NO3 and most would come as NH4 from fish food waste.


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## happi

plantbrain said:


> How where those NO3's measured?
> Also, which plants?
> 
> Mic umbrosum was among the 1st ones we found that did not do as well below 10ppm NO3.
> 
> If you have soil, or ADA As etc...then the water column is not the only source etc, but with plain sand, this can be done without influence from other sources etc.
> 
> I've noted smaller dia of the stem plants under stronger N and P limitation, about 30-50% smaller diameters(or leaf length's). This was for Myriophyllum matogrossense in an ADA run tank.
> 
> At 15ppm or more, they grew much larger and at a higher rate of growth(2-3x). Same for P stellata and L. cuba among others. Some folks might like the larger sizes however, some say they like the smaller more stressed look.
> 
> Bonsai also hold this view often times as well. I love me some Bonsai for a very long time. But if it's just used to justify their ego's in a debate.......well, then that's another issue. Then it's really not about aesthetics.
> 
> I see the stunted discus folks howl over smaller fish, but in nature, they are never as big as the fat pigs we often have also, but perhaps folks want smaller fish to fit into their smaller tanks? I do not know there.......but one could make the argument.
> 
> Same for weedy species and slowing them down with less N.
> I think less P would be a better idea if you wanna force CO2/light etc at higher levels, otherwise go non CO2 to slow and reduce the sizes.
> 
> Then optima might be only .5ppm NO3 and most would come as NH4 from fish food waste.


it was sunset hygrophila which did not show any good growth until NO3 was hiting the 30ppm range, i tested it with the api test kit and i agree that nothing is ever 100% accurate. but i was dosing much more Kno3 during the plant growth was much faster. i do have high light and high co2 running on that tank.


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## BlueJack

plantbrain said:


> Still, a target of 10-30ppm is what I and the group in the Bay area cam eup with about 15 years ago and it's been pretty good


Kind of a dumb question...does this mean dose 10-30ppm 3X per week?... or is the 10-30ppm the total amount over the course of the week? Thanks


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