Unusual nitrate levels?

[Spyro]

So, I have:

• 90lt that's way overstocked with: Platies, couple of Mollies, couple of Guppies and Betta
• fairly new set up. About 2-2.5 months (-minus cycling. instant cycled with established filter. just regular kit filter)
• about 2-3cm of quarts black sand substrate
• Some Java fern and few small Anubias with regular tank kit light
• PH 7.4-6
• I dose with some salt and minerals for KH and GH as tap water is close to RO

ALL the general wisdom and everything I've read about tank maintenance, slow growing plants I have, stocking levels, etc tells me:
I should be changing water at least once or twice a week to battle ammonia spikes, nitrates, algae, dirty water, etc. due to overstocking.

Yet I have crystal clear water, almost no algae, 0 ammonia and steady ranging Nitrates between 5-10ppm. After a month of not changing water or cleaning anything. Just adding food for fish

Any ideas how this is possible? Java Fern and Anubias shouldn't be able to drain Nitrates at that rate from overstocked tank? And everything I read says that only way to keep nitrates from rising is with regular water changes.

P.S. I use API test solution. I even bought new one as I though mine surely has to be off or something = same result

 

[NannaLou]

I’m still quite new but Nitrates between 5 and 10 ppm are ok, you need to keep that measure less than 20 ppm. What are your Nitrite levels? These are the ones that appear as the Ammonia is broken down..this should be zero as well as the ammonia.

 

[itiwhetu]

Your nitrates are about right for this setup. Just keep doing what you are doing. I would naturally put some more plant in the tank including some floating plants.

 

[Spyro]

I’m still quite new but Nitrates between 5 and 10 ppm are ok, you need to keep that measure less than 20 ppm. What are your Nitrite levels? These are the ones that appear as the Ammonia is broken down..this should be zero as well as the ammonia.

Yeah, 5-10 ppm on overstocked tank after a month of no water changes are so ok that it leaves me baffled as to how it's even possible. Especially since I started with 20-30ppm after the last water change.
Nitrites are 0 as well

 

[Spyro]

Your nitrates are about right for this setup. Just keep doing what you are doing. I would naturally put some more plant in the tank including some floating plants.

I'll edit the original question as it seems I didn't posit correctly.

Yeah, It's too good. Especially after the disaster of my first tank setup attempt.

 

[Spyro]

Down to 0 Nitrates between last test (4-5 days ago) and now.

The only logical conclusion I can draw from this is:
1- Anubias and/or Java Fern are nitrate removing machines. Contrary to general consensus that they don't do much since slow growing.
It would make sense since they don't require any fertilizers, are not planted into substrate but draw nutrients directly from water column.
2- regular water changes to remove nitrates are fishkeeping myth

All fishkeepers can't be wrong so it must be 1. Anubias and Java fern are awesome

 

[itiwhetu]

I am always saying, plants plants plants are the answer to your fish keeping woes

 

[Spyro]

I am always saying, plants plants plants are the answer to your fish keeping woes

Definitely seems to be working good for me (for now at least)

 

[itiwhetu]

We tend to get hang up on testing for stuff. Just plant your tank out watch your stocking levels and do a 25% water change weekly, and the rest will take care of itself. And another hint always use a neutral natural substrate.

 

[AbbeysDad]

Down to 0 Nitrates between last test (4-5 days ago) and now.

The only logical conclusion I can draw from this is:
1- Anubias and/or Java Fern are nitrate removing machines. Contrary to general consensus that they don't do much since slow growing.
It would make sense since they don't require any fertilizers, are not planted into substrate but draw nutrients directly from water column.
2- regular water changes to remove nitrates are fishkeeping myth

All fishkeepers can't be wrong so it must be 1. Anubias and Java fern are awesome

Not to rain on your parade, but I have to question your nitrate test results. Regent #2 of the API freshwater test kit is notorious for separation that requires vigorous shaking and/or rapping on a hard surface to ensure a good mixture that prevents false readings.
Anubias and Java Fern are slow growers compared to many other plants so use little ammonia to result in lower nitrates.
Water clarity is really not a measure of water purity.
Routine periodic partial water changes to promote more pure aquarium water is NOT a myth.

 

[Byron]

I agree with AbbeysDad. I would surmise there is a flaw somewhere in the testing, and the Regent #2 requiring vigorous shaking for a good two minutes may well be it.

There is another problem looming, the growth of these fish, mollies are not small (if they are healthy and grow that is). But what is the GH? What specific "salts" are you are adding and what is the resulting GH?

 

[Spyro]

Not to rain on your parade, but I have to question your nitrate test results. Regent #2 of the API freshwater test kit is notorious for separation that requires vigorous shaking and/or rapping on a hard surface to ensure a good mixture that prevents false readings.
Anubias and Java Fern are slow growers compared to many other plants so use little ammonia to result in lower nitrates.
Water clarity is really not a measure of water purity.
Routine periodic partial water changes to promote more pure aquarium water is NOT a myth.

I doubt that test result is incorrect.
For starters- I'm 42 yrs, got no problem shaking things for 2 min or seeing colors.
Second- If your theorem about test result was right:
I'd have widely inconsistent results on multiple tests. Odds of having incorrect test result while having consistently and uniformly dropping Nit levels while getting the same result on retests at every test; Well, odds of that would be astronomical.

Scientific method points to 1 conclusion thus far: 'anubias/Java Fern are slow growing thus they don't pull much ammonia/nitrates out of water' is widely held belief but logical fallacy none the less.
Also logical argument could also be: just because a plant grows much faster it doesn't necessarily mean it's pulling more ammonia/nitrates out of water column. It could be growing fast by using fertilizers/additives and not pulling much ammonia/nitrates out of water at all.

Anyhow, we'll see if results hold up or not over time.

P.S. I've done some research since getting interested in above curiosity:
Regular change of water and stocking level seems to be popular consensus; But there are quite a few fish keepers out there that have contrary opinion. A lot of them didn't change water in 30 years, a lot have massively overstocked planted tanks with no issues, etc. And a lot of them claim to be very experienced fish keepers.
Seems that there is more then one theory on the subject of water changes/nitrates/water quality.
Interesting.
I'm sort of scientific method testing over accepting general consensus so I'll test it out. It pokes my curiosity when I see different theories and I like to test it out.
Next test in scientific method: remove some Anubias; then all; then Java Fern and observe results. If it's not them: we'll know by resulting change in parameters when they are removed and reintroduced to the tank.

I'll post experiment results in due course

 

[AbbeysDad]

I'll just merely add that if one of the two regents (or both) becomes compromised, the test results may easily be consistently inaccurate. Consistency does not mean accuracy. I just can't buy that an overstocked tank with just anubias and java fern can yield zero nitrates after a month with no water changes.

 

[Spyro]

I'll just merely add that if one of the two regents (or both) becomes compromised, the test results may easily be consistently inaccurate. Consistency does not mean accuracy. I just can't buy that an overstocked tank with just anubias and java fern can yield zero nitrates after a month with no water changes.

Yeah, I was very surprised as well; especially since everything I read about anubias/Java fern is contrary. I even went and bought fresh test kit to eliminate that possibility.
We'll see when I remove Anubias/Java Fern if there is another factor or not.

1 thing I can definitely conclude: Anubias/Java fern don't punch well when it comes to bang for the buck value. The cost for the setup is definitely not economical way to get nitrates out of water (if anubias are indeed responsible)

 

[StevenF]

90lt that's way overstocked with: Platies, couple of Mollies, couple of Guppies and Betta

You say it is way overstocked but without any numbers how many fish it is impossible for anyone to evaluate the stocking level. In your opinion it isoverstocked but others may disagree.

I doubt that test result is incorrect.
For starters- I'm 42 yrs, got no problem shaking things for 2 min or seeing colors.

To know for sure make a nitrate reference solution with a known concentration of nitrate. Then measrue the reference solution with both of your test kit.s This will tell you with 100% certainty if one of your test kit is wrong.

Down to 0 Nitrates between last test (4-5 days ago) and now.

The only logical conclusion I can draw from this is:
1- Anubias and/or Java Fern are nitrate removing machines. Contrary to general consensus that they don't do much since slow growing.
It would make sense since they don't require any fertilizers, are not planted into substrate but draw nutrients directly from water column.
2- regular water changes to remove nitrates are fishkeeping myth

Question are the plants actually growing. If the plants are growing then they are consuming nitrate. Plants can only consume nitrate if they grow. If they don't grow they likely will not consume any nitrogen. If you have no growth and nitrate stays stable or drops, then you might have created a place with low oxygen concentration that is ideal for the special bacteria that can convert nitrate to Nitrogen gas.

Plants will consume nutrients wherever they are. if they are only in the substrate they will remove it from the substrate. But if they are in the water column they will take those. In general plants need water soluble nutrients, Nutrients in the vast majority of tanks have nutrient in the substate and in the water column.

Regular water changes do control nitrates if you cycle enough water frequently enough. The problem is is that Some people seen to think a 10% water change every few weeks is enough. Water changes do work if you do it once a week consistently. And it that doesn't reduce nitrate levels they you need to replace more water during the once a week water change. Also note a water change isn't the only way to to remove nutrients from the water. When plants growth consume nutrients. And periodically trimming and removing excess plants will remove nutrients from the water.

Furthermore it is important to note that water change are not just about reducing nitrate, They also reduce excess potassium sodium, and micro nutrients. water changes also help stabilize GH and KH levels. you should always do water change. Many only do water change only when nitrtes get high. Or if the nitrate levels stay low don't do water changes at all. If you don't do regular water changes the water will eventually become toxic even if the nitrate levels stay low. A usfulll video for water changes.