Nitrate frustration

[applescruff]

I have a 30 gallon established freshwater tank. I’m having an issue with getting the nitrate level down to zero. I have reduced the number of fish in the tank and have reduced the amount of food I’m giving them. I have the need to make water changes twice a week or sometimes even three changing anywhere from half to two thirds of the water in an effort to keep the nitrate level below 10. Sometimes even after changing two thirds of the water the nitrate level only improves very little. I have tested the water coming out my my tap and the level seems to be zero.
I do have four or five real plants in the tank and plenty of airation.
Any suggestions would be appreciated.

 

[Aiken Drum]

Why are you trying to get nitrate to zero? In normal circumstances its impossible to get nitrate to zero.

 

[Aiken Drum]

Nitrate is the end product of the nitrogen cycle. Waste ammonia is consumed, and nitrate comes out the other end.

Typically 40ppm of nitrate is considered a safe level of nitrate for fish. Your plants will need nitrate as its an essential nutrient for their health and growth, and nitrate below 10ppm could cause a nutrient deficiency. 20ppm nitrate is a good minimum level for healthy plant growth.

Nitrate is typically removed from your tank through water changes. Lets say at 20ppm, change half the water for clean (0ppm) water, your nitrate will go down to 10ppm. Another 50% water change it will go down to 5ppm. Every 50% water change will cut the nitrate in half, so nothing short of a 100% water change with clean water will get nitrate to zero. And come back the following day, the nitrogen cycle will result in more nitrate being added.

Plants will take up a little nitrate. But unless you are heavily planted with fast growing plants, fertiliser and strong lighting, those plants arent going to take up noticable amounts of nitrate. And if they did remove all the nitrate you would be in a situation where you would need to dose nitrate artificially back into the water so the plants arent adversely effected by a nutrient deficiency.

There is chemical media designed to remove nitrate. But if you can keep your nitrate no higher than 40ppm through a weekly water change, no need to chemically remove it.

Many people have nitrate in their tap water, which makes controlling it more difficult. Here in the UK 50ppm of nitrate is the legal maximum. I have 7ppm. Getting low nitrate would be very difficult for me. I think 20ppm is legal in the USA for drinking water.

 

[Colin_T]

Hi and welcome to the forum

Grow floating plants like Water Sprite and Duckweed on the surface of the tank. They will use the ammonia and help keep the nitrates down. If you get too many plants, sell or give them away, or throw them on the garden as a mulch.

 

[applescruff]

Why are you trying to get nitrate to zero? In normal circumstances its impossible to get nitrate to zero.

From articles I have read I was under the impression that any nitrate in the tank was very harmful to fish.

 

[Aiken Drum]

Ive never seen a reliable source that advocates a need for zero nitrate in a freshwater aquarium. I would be concerned that anyone stating that is confusing nitrite and nitrate. There might be a need for close to zero nitrate with saltwater as SW fish and coral is much less tolerant, but you tend to stock to much lower bioloads with SW and the filtration is different so that anaerobic bacteria can grow which consumes nitrate and releases nitrogen gas.

I can accept that lower is better, and that high nitrate can cause long term health issues, but generally speaking nitrate just isnt that harmful. If a weekly water change keeps nitrate somewhere in the 10 to 40ppm range thats fine. Many people keep fish in much higher nitrate than that.

Its a balance between how much work you are prepared to do with water changes and what level of nitrate you are prepared to tolerate. And as said a planted tank needs some level of nitrate.

 

[applescruff]

Thanks

Thank you for your knowledgeable advice. I feel like you have taught me something I needed to know about nitrates .

 

[m.j.gomez]

Thank you for your knowledgeable advice. I feel like you have taught me something I needed to know about nitrates .

Hello, have you thought of growing terrestrial plants on top of tank. They keep my tanks at a steady 20ppm. All I need to do is a 25% water change every couple of wks to clean substrate, replenish minerals & trace elements used up by fish.
I like to use golden pothos(2nd pic). It grows rapidly & I like how it looks. Some people like to use sweet potato(1st pic) & some will grow vegetables. If the plant you choose is using up to much nitrate all you have to do is trim roots. Heads up, pothos vine causes irritation if chewed on by other pets like cats & dogs. Hopefully this helps!!!!!

 

[applescruff]

Nitrate

Why are you trying to get nitrate to zero? In normal circumstances its impossible to get nitrate to zero.

I was under the impression if I had any nitrates it was dangerous for the fish. After reading all these comments I now see I was knocking myself out for nothing . Thank you.

 

[Joe_D]

Yeah, nitrate is not toxic to fish unless it is at very high levels.
Besides, plants need some nitrate to grow and prosper.

BTW, aquarium water is great for watering house plant,
In fact, I soak my "air" plants in aquarium water (once a week) and they are growing great with no other fertilizer.

 

[Colin_T]

Any ammonia, nitrite or nitrate is harmful to fish. However, nitrates are less toxic to fish than ammonia or nitrite. You need to keep ammonia and nitrite at 0ppm at all times. You want to keep nitrates as close to 0ppm as possible and under 20ppm at all times. I say 20ppm should be the maximum for nitrates because levels above that affect invertebrates (shrimp, snails, etc) and can kill them at that level. Ammonia, nitrite and nitrate are all harmful to animals, birds, reptiles, people and fish. There is a known link between nitrites found in smoked & preserved meats, and cancer. The health departments around the world recommend avoiding anything with ammonia, nitrite or nitrate in. If it's dangerous to us and other animals, then it's dangerous to fish. Whilst fish might swim around in tanks with high nitrate levels and appear fine for several years, it does long term harm and does shorten their lives. You have to remember that fish evolved in water with 0 ammonia, 0 nitrite and 0 nitrate. Just because it builds up in aquariums, doesn't mean it's safe. So the lower the nitrates, the better it is for the fish and other organisms in the tank (except plants, which use nitrates as a food source).

As Aiken said, it's a compromise between the amount of work you want to do on a tank, and keeping the water as clean as possible without going overboard. A big (75%) water change and gravel cleaning the substrate once a week is usually sufficient to keep nitrates at a low level. Floating plants help as do plants growing in the gravel. And m.j.gomez's idea of terrestrial plants growing above tanks and having their roots in the water, is a great way to reduce nitrates and is quite a common practice in the UK where they regularly have 40-50ppm of nitrate in their tap water.

Plant plants, grow plants in pots above the tank, and do big weekly water changes and the nitrates should stay low.

Reduce feeding and reducing the fish stock will also lead to lower nitrates.

 

[Joe_D]

I have nitrate levels much higher than that and my cherry shrimp are doing great and multiplying,
Fact is, no one can really agree on what level nitrate is too high. B

BTW, nitrate occurs naturally in many lakes and ponds at various levels

Yeah, it may shorten the life of aquarium fish by a few months
However, nothing about an aquarium is natural .

 

[Andy Sager]

I have nitrate levels much higher than that and my cherry shrimp are doing great and multiplying,
Fact is, no one can really agree on what level nitrate is too high. B

BTW, nitrate occurs naturally in many lakes and ponds at various levels

Yeah, it may shorten the life of aquarium fish by a few months
However, nothing about an aquarium is natural .

Actually, there is a lot going on when you have higher nitrate levels. One of these is that your Ph falls as your nitrate level rises. The good news is that at a Ph level below 7.0, ammonia becomes the less toxic ammonium and while ammonium is used by your nitrifying bacteria as well as live plants, if you do a water change that raises your Ph to above 7.0 but not enough to eliminate all the ammonium, it converts back to the toxic ammonia and can kill your livestock.
It also does effect the fish in a negative way. If the scientist within you is curious , this is a study that confirms an issue with higher nitrates and lower Ph combined: https://academic.oup.com/conphys/article/8/1/coz092/5658492

 

[Joe_D]

NY PH is holding steady at 7.
In any event, like I said, no one can agree on how high a nitrate level is too high.
BTW We have very good water in my area from large open air reservoirs.

 

[Andy Sager]

NY PH is holding steady at 7.
In any event, like I said, no one can agree on how high a nitrate level is too high.
BTW We have very good water in my area from large open air reservoirs.

I can't say that it still is the method but we used to use the " If nitrates are reducing Ph, they are too high" method back in the day. That was pretty universal.
As for no one can agree.... I have to differ. That may apply to the average hobbyist but the study in the link I posted has definitely numbers of effects from different levels of nitrates in the water.

It's good to see that NY still has good water. I used to buy fish in NY. I had it too in NJ back in the 60s and early 70s when I lived there. It has changed since I left.

 

[Joe_D]

BTW I live in upstate NY not NY City.

I will just say one more thing...
For every article one can point to that says that nitrates are toxic to fish in one respect ore another there is anther article that says the opposite...as long as the levels are not very high

There are are many reports of aquariums with high rates of nitrate with no bad effects.
So, what are we to believe?

 

[Colin_T]

There are are many reports of aquariums with high rates of nitrate with no bad effects.
So, what are we to believe?

There are lots of reports of people claiming their fish are doing well because they keep them alive for 6 months. I used to have customers coming into the shop thinking they were doing well because their neon tetras lived for 6 months before dying. When I told them neons can live for 4-5 years they went "oh".

I have seen plenty of tanks that didn't get sufficient water changes and had high nitrates and a lower than adequate pH. The fish in these tanks slowly died off over the course of a year and the owners thought it was natural courses. It wasn't.

If people add fish to tanks that have a high nitrate level, the majority of those new fish die within a very short space of time.

-----------------

I recommend keeping nitrates as low as possible and under 20ppm because this is the number I was given decades ago when it came to keeping invertebrates alive in marine tanks. Most corals, anemones, shrimp, crabs, clams, etc, die if the nitrates go above 20ppm. If they don't die, they are severely stressed and weakened due to the high levels. The same applies to freshwater fishes and invertebrates. You might have some shrimp that live in water with 30-40ppm nitrate, but they would do better with no or low nitrates.

Nitrates don't naturally occur in clean waterways. Fish didn't evolve to deal with them. Just because fish and shrimp can survive for periods of time in water with high nitrates, doesn't mean they should be forced to.

Do you enjoy being forced to live in a polluted city and breath in smog all the time? Probably not. We can live in cities like this for years and seem alright. But we are poisoning ourselves and shortening our lives. Why do you think cancer is so common now. Going back 100 years ago cancer was almost unheard of. Now 1 in 3 people will get it.

Most aquarium fishes will live a lot longer than they do in the average aquarium if conditions are good. Freshwater angelfish, Corydoras and bigger species of rainbowfish can live for 10 years. Betta splendens used to live for 5-6 years. Lots of fishes die prematurely in aquariums and most of the time it is stress related, and that stress is usually associated with poor water quality and a dirty tank.

If you want your fish and other aquatic pets to live the maximum amount of time, try to keep nitrates as close to 0ppm as possible, and under 20ppm at all times.

 

[Andy Sager]

BTW I live in upstate NY not NY City.

I will just say one more thing...
For every article one can point to that says that nitrates are toxic to fish in one respect ore another there is anther article that says the opposite...as long as the levels are not very high

There are are many reports of aquariums with high rates of nitrate with no bad effects.
So, what are we to believe?

Qualify the sources of your information. You'll notice mine are not from hobbyists.

 

[Joe_D]

Who else knows more about keeping fish than those who kept them over the years" :

Anyone can write an article but I will only believe someone with real hands one experience with something

 

[Colin_T]

Who else knows more about keeping fish than those who kept them over the years" :

Anyone can write an article but I will only believe someone with real hands one experience with something

I have been keeping fish since the late 70s. I spent 20 years working in the wholesale and retail pet industry. I was a member of various fish clubs and have been on fish forums since the interweb thingy kicked off with Windows 95. I have kept and bred most aquarium fish that have been in Australia, including numerous native fishes that I had to collect because they weren't available in shops, some weren't even described in the scientific literature. I used to collect fresh & saltwater fish and other aquatic organisms for myself and shops. I worked in an aquaculture facility where we grew aquatic plants and native fishes, as well as a few other fish species. I had a fish room with 40 tanks. I have seen most fish diseases and helped thousands (probably a lot more) of people set up and care for their fish. People that follow my directions when caring for fish, usually do very well with them. Hopefully that's hands on enough for you