Nitrates

[Country joe]

I look at lots of videos on you tube, and regarding on cycling, there's a few stating, when your tank is fully cycled it will start to show nitrates, well my aquarium after nil readings fish were added on 4th of May, recently did a nitrates test, and it showed nil, that's nearly 3 months, is this normal?

 

[Essjay]

You have plants, so yes it can be normal.

Nitrate in tanks comes from 2 sources.
The first is tap water. The UK legal limit is 50 ppm and some places are close to that. Other places are well below - for example my water company gives my tap nitrate at 3 ppm and my test kit is higher than zero but lower than 5 which agrees with the water company.
The second is made from ammonia excreted by fish.

When a tank has a lot of plants they take up ammonia and convert it into protein not nitrite, so there's nothing to be converted to nitrate. With my low tap nitrate and plants my tanks run at zero nitrate. If there are enough plants that they need more ammonia than the fish make they then use nitrate if there's any in the tap water. So a heavily planted tank in a place with low nitrate in tap water can easily have zero nitrate.

However, in a tank with no live plants, even with low tap nitrate there should be some nitrate detectable particularly just before a water change. And a heavily planted tank in an area with high tap nitrate will probably always have some nitrate present.


What is the nitrate level in your tap water, both with your test kit and the water quality report on your water company's website?

 

[10 Tanks]

I look at lots of videos on you tube, and regarding on cycling, there's a few stating, when your tank is fully cycled it will start to show nitrates, well my aquarium after nil readings fish were added on 4th of May, recently did a nitrates test, and it showed nil, that's nearly 3 months, is this normal?

Hello Country. I'm here in the US. In the part of the country I live in, we have near neutral tap water. It may be a little acidic. I believe the pH is roughly 6.8. Here's my opinion. If you have a tank less than say 115 liters, you just change half the water a couple of times a week. Use a water treatment and a bacteria starter every time you change the water. Now, if your tank is more than 115 liters, then change half the water every five days and use the same water treatment and bacteria starter. I don't worry about forms of nitrogen building up in my tanks, because I change the water so often, those toxins never build up to anywhere near toxic levels before I remove them when I change the water. If you don't keep too many fish and just feed those you have a little food every couple of days, you've got no worries. Just follow an aggressive water change routine.

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[Essjay]

In areas with high tap water nitrate it doesn't matter how many water changes you do, the lowest nitrate they can get it is the same as the level in tap water. If that's 40 ppm in tap water, it's 40 ppm or more in the tank water.

 

[10 Tanks]

In areas with high tap water nitrate it doesn't matter how many water changes you do, the lowest nitrate they can get it is the same as the level in tap water. If that's 40 ppm in tap water, it's 40 ppm or more in the tank water.

Hello. 40 ppm nitrates is really high for public drinking water, but not too high for fish. Most hardy fish species aren't going to notice this level, but you don't want it to go much higher. I suggest just changing out half the tank water at least once a week to maintain a steady water chemistry.

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[Essjay]

40 ppm is out of date I'm afraid. Most reliable sources now give 20 ppm as the maximum nitrate, with some fish needing lower than that. It is now believed to be a cause of hole in the head in cichlids.

See post #9 here.

Byron's Legacy

Byron Hosking was a long standing member of the forum. He was very knowledgeable about many aspects of fish keeping with many years spent in the field researching and was always willing to share his knowledge. Many members of the forum have benefited from his expertise. Sadly Byron passed away...

www.fishforums.net

40 ppm is under the limit set by the UK and USA. You'll read that the USA limit is 10 ppm but that's on a different scale than the one used in fishkeeping. That 10 ppm USA upper limit converts to 45 ppm on the fishkeeping scale. In places where there is farming run off into waterways, nitrate is often high.

 

[10 Tanks]

Hello again. I'll stay with my original post. If you keep nitrates consistently in the 40 ppm range most, aquarium fish won't have a problem with it. Just change most of your tank water at least every few days to maintain a steady water chemistry.

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