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High Nitrates (>120ppm)

Epiphyte

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Hemel Hempstead
So this has been plaguing me for a while now and I can't quite work out why. Hopefully some experienced folk on here can assist.

My tank is a Juwel 350L tank, running the stock filter plus an Oase Biomaster 600 Thermo. Lighting is some home brew setup which should be around the 8000 lumen mark (I'd call it medium lighting), CO2 injection (light green drop checker) from 4hr before lights on to 1hr before lights off. Ferts dosing is 35ml of TNC complete per day via a dosing pump, as advised by Aquarium Gardens.

Plants wise, lots of stem plants in the background, big pieces of bog wood covered with epiphytes. I'd say there are well over 100 individual plants in the tank. Substrate is, unfortunately, Seachem Flourite.

Fish stocking is around 30 tetras of various species, 8 Sterbai Catfish, 2 SAEs, a single whip tail catfish, a blue ram, 10 Nerite Snails and about 6 or 7 Amano shrimp.

Water changes are 50% weekly with tap water. My tap water comes with around 30ppm nitrate.

My issue is nitrates. Ammonia and nitrites read as zero, but nitrates are often as high as 120+ppm. The tank has little algae, just a small amount on the glass which the snails munch away at, but otherwise is clear. I've had some melt from some plants but that's starting to stabilise now. The fish are fed every two days and the rummynose are so piggish they wouldn't let a scrap go to waste.

What could be causing such a high nitrate reading? I know TNC complete has nitrogen in it, could I be overdosing?

Here is my API master test kit nitrate colour, it's pretty strong.
20201222_151557.jpg

I did a 50% WC yesterday and may do another today. Is there anything else I can try to improve my nitrate readings?
 

Zeus.

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Hi
Think, your dosing too much of TNC!
35ml 3x times per week!
That would be with a very high plant mass I think?
1608727014185.png

So the OP is dosing x3 over recommended STD dose which IMO is about 50% EI depending on what we use to compare - NO3,PO4, K or Fe

So at the OP dosing 20ppm NO3 max from TNC, 15 ppm NO3 from WC, but that still leaves 90 ppm NO3 - So its coming from something else eg substrate, dead livestock in tank or test kit no good
 

Epiphyte

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Thanks all for the advice. I've stopped the dosing pump for now until I get the volumes calculated correctly.

I was recommended 35ml per day (1ml/10L) by Dave at Aquarium Gardens. I'm a little new to the planted side of the hobby so took his word as gospel and didn't do much extra research on it.

Been dosing this way now for around 2 months, perhaps 2 1/2.

I assume I can reduce this figure significantly?

To give an idea of plant mass, here's my tank (Angels added yesterday so can't assume they would be effecting my nitrates as added just before the test).

20201223_134509.jpg
 

jaypeecee

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I was recommended 35ml per day (1ml/10L) by Dave at Aquarium Gardens.
Hi @Epiphyte

I seem to recall something similar happening a good few months ago and the UKAPS member running into problems with excessive dosing of TNC Complete. It may have even been just a year ago. The UKAPS member was hoping to get back to Aquarium Gardens about this but they were closed for some reason. Perhaps it was Christmas or at the beginning of the pandemic. I'll have a quick look to see if I can find the thread.

JPC
 

jaypeecee

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Hi @Epiphyte

Well, well...would you believe it? I found the thread that I was looking for. This link will take you to the bit where it started to get interesting:


JPC
 

GHNelson

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TNC Complete Website
1ml per 10 litres of tank water 3x per week will give a dose similar to the Estimative Index levels.
Be sure to change 50% of your water once per week to remove organic waste from the plants.
 
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Can you reduce dosing by either changing the output of the doser so it only does 15ml per day which would be more inline with 35ml x 3 times per week or set it to dose every other day?

The tank has little algae, just a small amount on the glass which the snails munch away at, but otherwise is clear.
My issue is nitrates. Ammonia and nitrites read as zero, but nitrates are often as high as 120+ppm.
Now there's something to ponder for the next person who is worrying nitrates cause Algae. Tank looks great as well :thumbup: Just in case make sure you don't test after using water conditioners, they are know to skew the test.
 

Zeus.

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Hi Zeus
The member has been dosing 35ml daily!
Need to establish how long?
hoggie
:oops:, missed read your post m8, you was advising 35ml x3 week

So 1.0ml per 10liters x7 a week
1608738430309.png

So its basically a little higher than 'the double triple dose' to match EI dosing - however still a little low in Mg IMO
 

GHNelson

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Hi Bud
Obviously....the plan of action is to get the Nitrate Level down!
Before I go into that....test your tapwater Nitrate levels with the test kit you used on the aquarium water;)
Let me know the reading.
Stop dosing the TNC Complete for the time being!
Do your normal water changes.

Do you have any fast-growing stem plants available?
Do you have Micro/Trace available to dose?
Do you have Magnesium Sulphate/Epsom Salt?
Cheers
hoggie
 

PARAGUAY

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I like the API tests for ammonia nitrite but on nitrates it's easy to error and the colour is so close to wide differences in what level of nitrate you may have
 

Epiphyte

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Thanks everyone for the excellent replies. So the general theme to this is certainly overdosing of TNC Complete, which makes entire sense. I know many on here are advocates of EI with dry ferts but that's not a path I'm really able to go down just yet as I need the system automated as work takes me away from home regularly (once covid goes!)

So given I need to reduce the nitrates (I'm doing daily 50% water changes) and keep them at a sensible level, can anyone suggest a good dosing volume?

I need to get reading into what all the different components of the fertiliser is and what the tank requires, but naturally I'm unable to "pause" the tank whilst I learn what's best.

@hogan53, mentioned above tap water is 30ppm, so I feel up to 50-60ppm would be a more "normal" reading. We live in the same area it seems so my water should be the same as yours

@PARAGUAY, do you recommend a different kit? I know API seems to be the standard go to but I've never been a huge fan of it if I'm honest!
 
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Siege

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“So given I need to reduce the nitrates”

Why is it a given?

It is important to note that there are 2 forms of nitrate,
  • inorganic nitrate arising from tap water and plant food. This is safe for fish.
  • organic arising from excess food, melting plants, waste etc. This is unsafe.

The test kit won’t tell the difference.
It is also worth noting that the nitrate test kit is not known to be the most reliable.

As your tank is going well, then why test for it at all?

If you are that worried about nitrate slightly reduce plant food and look at your plants. A better idea would be to do a larger water change. If your process is set up easily instead of doing 50% do 80%. This will also remove things that your test kit isn’t telling you.

I think your worries about high nitrate are unfounded. The issue lyes from mixing advice..
You initially take good advice and follow how one place run their tanks, you like them so want to copy their processes so you do, it is going well.
Then you read something that says Nitrates are bad. This goes against what you’ve already been told and is confusing.
This is a common mistake, it is easier and will give you a better result if you copy the processes of 1 or 2 people to begin with. You know it works as you’ve seen the consistent results. 👍😃
 
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dw1305

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Hi all,
there are 2 forms of nitrate..........
  • organic arising from excess food, melting plants, waste etc. This is unsafe.
That is it. It isn't so much there are two forms of nitrate (technically they are all NO3- ions), it is <"the journey"> that interests us. Usually NO3 is the <"smoking gun"> of previously elevated levels of ammonia (NH3) and nitrite (NO2-), and the damage has already been done.
inorganic nitrate arising from tap water and plant food. This is safe for fish.
When you add NO3 (via a salt like potassium nitrate (KNO3), or TNC, or your tap water) that fixed nitrogen has already undergone <"microbial nitrification"> and that NO3- has always been NO3-.
and keep them at a sensible level, can anyone suggest a good dosing volume?
Just add the same volume of TNC, but twice a week? and watch <"plant growth"> and <"leaf colour">. As the others have said the plants will deplete the nutrients fairly effectively.
I like the API tests for ammonia nitrite but on nitrates it's easy to error and the colour is so close to wide differences in what level of nitrate you may have
Yes, this is also an issue, you need to dilute the tank water sample with a known volume of RO water until you get a much less strong red colour and then multiply the value you get by the dilution factor. I'm not a fan of nitrate testing, there are a <"number of issues">, but in your case you definitely have a lot of nitrate.

cheers Darrel
 
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There are three levels of dosage for TNC Complete:
  • ”Standard” dose for low-tech tanks: 1ml per 10 litres, once a week.
  • ”Triple” dose recommended by the manufacturer as an approximation of EI: 1ml per 10 litres, 3 times a week. This actually gives a slightly lean version of EI.
  • “Double-triple” dose recommended by Aquarium Gardens: 1ml per 10 litres, 6 or 7 times a week. This gives a rich version of EI with lots of nitrate. This is what the OP is dosing.
I have used the “double-triple” dose successfully on my heavily planted nano tank, but I would only recommend it for small tanks with a heavy plant mass. For larger tanks you are much better off using DIY salts to concoct your own mix; a “double-triple” dose of TNC Complete would be very expensive in a larger tank.

I would recommend the OP to switch to DIY salts, which would be way cheaper and would allow him to tailor the levels of each nutrient. You can make your own stock solution that you then add to your tank or put into your auto-doser. He’d want to use hardly any nitrate due to the high-ish level in the tapwater.

The salts are easy to buy online:
  • Potassium nitrate KNO₃ - although you might not need this with 30ppm NO₃ in your tapwater.
  • Monopotassium phosphate KH₂PO₄
  • Potassium sulphate K₂SO₄
 
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Zeus.

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Another solution is to make your own EI DIY mix and not use TNC @ EI levels and account for the NO3 in your water
Get your main salts from APFUK and some KSO4 from ebay plus some E300 and E202
1608816716434.png


mix it up and dose 35ml daily with AIO @EI levels for £0.21 a week
 

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