Are nitrates bad in planted aquariums?

Jacob Coleman

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I have a planted tank which is stocked with around 20 small fish, the last couple of times I have tested the water my nitrite has been at 0 but my nitrate has been around 20 on the api test strips, according to the test strips this isn’t bad.

I was wondering weather I should try to lower the nitrate or leave it because the plants can use it to grow?
 

dw1305

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Hi all,

The first thing would be "do the plants and fish look healthy?"

Assuming they do? Then there isn't much wrong with what you are doing at the moment.
I was wondering weather I should try to lower the nitrate or leave it because the plants can use it to grow?
Nitrate (NO3) levels usually go down in a planted tank over time. You probably have <"fairly high NO3 levels in your tap water"> (you can find out from your water supplier), because of where you live. Most of the south and east of the UK has hard water with high NO3 levels.

Personally I don't <"test for nitrate">, I use a different method (the <"Duckweed Index">) for estimating nutrient levels.

Have a read through the linked threads and they should answer most of your questions.

cheers Darrel
 

rebel

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As @dw1305 mentioned, if you post a photo, we can have a look.

For the most part, I'd leave 20ppm of Nitrate alone. Just continue with weekly 20-50% water changes as usual. Fish and plants love water changes.
 

dw1305

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Hi all,
if you post a photo, we can have a look
The plants and fish both look fine.

All three <"Rummynose Tetra species"> are quite sensitive to declining water quality, and don't really like hard water, so the fact that their "noses" are nice and red suggests that there isn't a lot wrong.

You mainly have slow growing plants, you could try adding some faster growing stems and or floating plants. I like floating plants, but I know they aren't to everyone's taste. If you want some, PM me and I can send a mix.
I am running a Ehiem pro4 350 and it has two trays full of biohome ultimate,Ehiem substrat pro and bio rings so I think it may be something to do with my tap water.
Aerobic microbial filtration won't deplete the nitrate (NO3), but your plants will, assuming that other nutrients aren't already limiting plant growth.

The filter media micro-organisms will convert ammonia (NH3) to nitrite (NO2) and eventually NO3. You've gone from three hydrogen (H) to three oxygen (O) so you you've added an acid (3 H+) and you've consumed a base (3 O-). Your water will supply the base (2 CO3-), but it is the <"oxygen that is really important">.

A lot of conversation about biological filter media talks about a possible final stage of the nitrification cycle, where anaerobic denitrification converts NO3 to N2 gas. I'm not a fan of this approach.

Have a look at <"Media set up">, the whole thread is worth a read.

cheers Darrel
 

tam

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I'd only worry if it was steadily increasing - that would imply that you are producing more than your plants/water changes are able to cope with and at some point you'll run into an issue. If it stays steady where it is and everything looks good, don't worry too much.
 

jms127

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Agree with all the above, are you using any type of aquatic plant fertiliser? You may be fine with tap water alone if this is a fairly low tech setup but as plant mass increases the demand for nutrients increases and the waste from fish/ content of tap water may not be enough to provide them.
Have you considered an all in one liquid fertiliser? Delivered at baseline values should be sufficient, but may not be needed yet.
 

Jacob Coleman

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You mainly have slow growing plants, you could try adding some faster growing stems and or floating plants.

I have added hygrophila siamensis 53B and some Amazon sword in the background to increase the plant load and have some faster growing plants reducing algae (which has worked) and to use excess nutrients. This is a learning curve I’m 16 and been keeping aquariums for under a year and only recently started planted aquariums. So thanks for all the advise:)
Also floating plants would be great because that are fast growing.


are you using any type of aquatic plant fertiliser?

Yes I am using Tropica specialised and dosing one pump a day.
 

JMorgan

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Just to add - rummy noses can also get a kind of shiny greenish blob of colour on the top of their heads, especially when they're happy. I mention it because in certain lights it can be quite startling, and having read stuff about how sensitive these fish are to water quality my immediate reaction (some years ago now thankfully) was, "Oh blahblahblahblah I've made them go green!" followed by much panic fuelled searching online!! :arghh:
 

rebel

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Based on your picture I think you need to urgently do























absolutely nothing different. :) Soldier on.
 

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