High nitrates, but water changes don't help. Any ideas?

[Shrimplover1]

I have a 55G tank with plants and a bunch of shrimp and fish. All my water values were always stable, but I had to put in some Nitrofurazone and API Pimafix (separately, about a week apart) to try to fix some cotton mouth on a few of my neon tetras.

Now I constantly have high nitrate values between 40-80ppm. I did a 25% water change today, another one 3 days ago, and also after pimafix, and the nitrofurazone. I never go longer than 2-3 weeks and I change 20% or so each time.

Any ideas why this is going on?

My ammonia is 0ppm, my nitrites are 0ppm, nitrates between 40-80ppm (the color is somewhere inbetween. I can't really tell if its one or the other). Temp is 78F, tank has been setup for about 8-12 months. Fluval 307 canister filter. Fish are mostly small rasboras, 8 neon tetras, 6 x ray fish, 8 guppies, and about 8 glofish tetras. Nothing new has been put in the tank other than a breeding mop (pic here: https://i.ebayimg.com/images/g/JCUAAOSwDQJiSQba/s-l1600.jpg ) and no new fish have been added for a long time. No plants either

The only thing I can think of is I cleaned half the sponges in my canister filter with water, but I put Prime in it, so it didn't have cholorine.
I also tried adding an additional dose of prime into the water to try to reduce the nitrates, but it didn't do anything.

 

[TwoTankAmin]

Prime messes with test kits. If you had screwed up your cycle you would see ammonia and or nitrite.

How old is your nitrate kit? Are you beating heck out of bottle #2 if it is an API kit?

Did you test your tap for nitrate?

I clean my canisters thorought twicce a year, not issues so far and I have 3 of them and the longest had been going for just under 20 years.

 

[Colin_T]

The medication might have messed up the filter.

Check your tap water for nitrate. If it is free of nitrate, do bigger (75%) water changes and gravel clean the substrate every day for a week.

Small water changes don't do anything to reduce nitrates.
If you do a 25% water change each week you leave behind 75% of the bad stuff in the water.
If you do a 50% water change each week you leave behind 50% of the bad stuff in the water.
If you do a 75% water change each week you leave behind 25% of the bad stuff in the water.

 

[Shrimplover1]

Prime messes with test kits. If you had screwed up your cycle you would see ammonia and or nitrite.

How old is your nitrate kit? Are you beating heck out of bottle #2 if it is an API kit?

Did you test your tap for nitrate?

I clean my canisters thorought twicce a year, not issues so far and I have 3 of them and the longest had been going for just under 20 years.

I've been using prime since the beginning and haven't had high values like that. I am properly following the directions and shaking for the time directed. I have two API test kits and both expire on 2/26. My new tank (shrimp only 10G) doesn't have the same problem, so I don't think its the water that comes out of the faucet. I can test tomorrow and get back to you if the water itself tests high.

 

[Shrimplover1]

The medication might have messed up the filter.

Check your tap water for nitrate. If it is free of nitrate, do bigger (75%) water changes and gravel clean the substrate every day for a week.

Small water changes don't do anything to reduce nitrates.
If you do a 25% water change each week you leave behind 75% of the bad stuff in the water.
If you do a 50% water change each week you leave behind 50% of the bad stuff in the water.
If you do a 75% water change each week you leave behind 25% of the bad stuff in the water.

Will try this, I was just afraid to do too big of a water change because I don't want to shock the fish. But will try it.

 

[GaryE]

Test your source water. California has big time agriculture and a drought...

 

[Naughts]

Test your source water. California has big time agriculture and a drought...

Does dry weather increase nitrates in source water? How long do you think it would take to 'dilute' them after it rains?

 

[StevenF]

Does dry weather increase nitrates in source water? How long do you think it would take to 'dilute' them after it rains?

Dry weather generally des not cause high nitrates. Wet weather however can. When it rains cause water run-off from farms. Farms typically use nitrate fertilizer If that gets into a river that is used for drinking water the nitrate winds up in your tap water. Excessive use of fertilizer can also contaminate ground water because the rain would carry the nitrate into the aquafer. Sewarg runoff can also increase nitrate. Most of the time sewage is aerated and treated so that it has no nitrate before the waste water is discharged in a river or the ocean. However in a flood caused by rain can overwhelm the treatment facilities causing Nitrate and ammonia to reach a river and contaminate water supply.

In the UK high nitrates are common in ground water because for hundreds of years people didn't now how to properly treat waste water or simply dumped in down a well or applied too much nitrate to farm fields. End result well water there often has high nitrate levels and it It could take centuries to undo the damage to the aquifers.

 

[TwoTankAmin]

Usually it agricultural and other commercial run-off that adds nitrate to ground water. From there it can get into the water supply. Also, the punlic water supply responsibility usually ends at the private property line. So your pipes are your to worry about not the water company. The water company battles nitrifying bacteria. they do not want them in the system because they create nitrate. However, they are not perfect and some bacterial cells can get through. This is not a problem for the municipal supply system.

But once the water is in private pipes things change. Many homes have a bathroom or utility sink or faucet that does not get used very often. And it is in the spaces there that the nitrifiers can colonize. So now you may actually be adding nitrate to the water without realizing it. What makes this possible is the use of chloramines as a disinfectant in the water supply. residual amounts eventually breaks down and what remains is ammonia.And this can feed the nitrifying bacteria. They can actually accumulate in our plumbing under certain conditions.

This is a quoted from a paper on this subject, I have colored blue the key points

3. Nitrification in Premise Plumbing
Over the last decade, the interest in premise plumbing from the water industry has increased.
Numerous studies have investigated different issues surrounding premise plumbing, such as
corrosion [78–81] and the growth of opportunistic pathogens [82–88]. Premise plumbing systems are an
area of the distribution system that can be overlooked by water utilities, since most premise plumbing
systems are not owned or maintained by the utility and most drinking water regulations do not address
premise plumbing, with the exception of the Lead and Copper Rule (LCR). Premise plumbing systems
are also made up of both hot and cold-water systems. The hot water systems within premise plumbing
can promote increased microbial growth over cold water systems and are completely unregulated by
the EPA. Premise plumbing systems can range from conventional single-family homes, multi-family
residential, healthcare facilities, institutional buildings (i.e., office buildings, schools, or universities), to
high-rise skyscrapers. The plumbing systems within these various building types are often unique and
have varying levels of complexity (e.g., the plumbing system in a high-rise building is going to be much
more complex than that of a single-family home). The varying levels of complexity in these different
systems makes a one-size-fit-all solution to premise plumbing water quality issues difficult. These
systems are subject to high temperatures, high surface area to volume ratios, variable flow patterns,
and extended periods of stagnation [89] which can lead to increased disinfectant decay, microbial
growth (including nitrification), loss of thermal control, and corrosion. These factors create a complex
environment that can make it difficult for utilities to maintain high water quality in these systems.
Figure 2 gives a conceptual model for how nitrification and general water chemistry conditions change
as water travels throughout a drinking water distribution system and into a premise plumbing system.
This section will explore different premise plumbing water quality issues and how they are impacted
by nitrification and vice versa.

Read the full paper ere if you wish https://www.mdpi.com/2073-4441/12/3/830/pdf
Bradley, T.C., Haas, C.N. and Sales, C.M., 2020. Nitrification in premise plumbing: A review. Water, 12(3), p.830.

 

[GaryE]

I've noticed a lot of postings over the years from people who live in industrial agriculture zones, specifically in the midwestern belt of the USA, who discovered pretty high nitrates in their tap. They're great consumers of water treatment products. That nitrate problem they have has led to some very confusing discussions about water, as someone in a clean water region like me doesn't get it til it's outlined.
It's why I'd test my tap if I were in a farming region.