Perpetually high nitrates no matter what I do! Dozens of water changes later.

[traxolotl]

Hello all, I have exhausted nearly every option and I am really hoping to find some answers on this site!!

I have been battling with nitrates for months to to no avail. I have a 40 gallon axolotl tank and I admittedly didn’t cycle properly to begin with, I was using test strips at the time and unaware of my tap nitrates, so after it seemingly tested at good levels on the strips after running with a little filter media and water from their old tanks, I put them in.

This didn’t last too long but neither did my ignorance, I experienced a cycle crash at one point and took my two axolotls out and tubbed them while I fixed it with all the proper equipment this time, liquid test kit and all. I fishless cycled the tank properly for over two months, had some problems along the way but figured out solutions to nearly all of them.

I say nearly because my nitrate issue persists no matter what I do. Throughout the entire fishless cycling they were testing very red, I did water changes attempt to get them down, but that didn’t help.

At one point I finally tested my tap, and it had about 20ppm nitrates. I realized that was unsustainable for my tank and thought I had found my problem. I purchased an RO system, some stuff to remineralize the water and buffer the PH, and started doing water changes with that. Unfortunately, that didn’t help though, even with 90% water changes.

A few days ago, I did a little experiment with the rocks I had in the tank for decoration, I set one in a cup of clean water for a few hours and tested the water it was in for Ammonia. The test came back over 1ppm Ammonia. I figured maybe this was my issue, there’s so much extra Ammonia leeching out of the rocks that’s all converting to nitrate overnight and causing it to perpetually be high. I removed all the rocks, did a 30 gallon water change, and tested the nitrates in the tank at 20ppm a few hours after the change. The next day though, they were red again. Less than 12 hours after the 30 gallon change. I figured maybe some leftover Ammonia from the rocks were just causing it and after one more change I’d be good, so I did another large water change. This brings me to today, and unfortunately, my nitrates are still testing red, probably 40ppm.

I just don’t understand what I’m doing wrong, I admit in the beginning of this tank I wasn’t as knowledgeable as I am now, but after months of research, keeping good husbandry, even buying chemical filtration meant to remove nitrates, nothing is helping. I see people posts tests that look like mine, and people say things like “have you never done a water change?” “This is MONTHS of nitrate build up!” But I have done probably 40 water changes just in the last two months!!! I feel like I’m going insane!

Here’s some info on my tank:

40 gallon breeder.

Substrate: quickcrete play sand (did not wash, wasn’t aware I should have at the time and I definitely paid for that, had cloudiness issues for awhile but got it under control)

Hardscape: three pieces of driftwood, boiled for almost 2 days straight. Two reptile heavy plastic hides/caves, one large slate rock from their old aquarium, as I said I removed the rest of the rocks after I figured out they were an issue.

Live plants: lots of Anubis, various swords, some ferns, and pothos growing out of the top.

Filtration: tetra whisper 45 gallon HOB with course sponge, nitrate filter pad, filter floss, biomax, and a bag of de-nitrate.

45 gallon sponge filter

Aquanet large sponge filter with media compartments, it has some boimax looking stuff, pebbles, and various sponge/filter pads.

Fluval 207 canister filter with all the media It came with besides the carbon, I replaced that with a bag of Purigen, and a bag of nitra-zorb. I replace/recharge the nitrazorb when It needs to be but obviously it’s not doing anything for my nitrates.



I’ve been asking for insight everywhere, here are some commonly asked questions you may have and their answers.

Q- have you been doing the nitrate test correctly?

A- yes, I’ve been shaking bottle 2 to all hell and then some, as well as the test itself. I’ve second guessed myself so much I’ve watched dozens of videos of other people doing it just to make sure I am in fact doing it correctly.

Q- is your nitrate test expired?

A- no, it shouldn’t expire for 4 years. This is even a new test I bought a few weeks ago because I had used the one that came with the master kit so much.

Q- have you cleaned your filters?

A- yes, all the media has been rinsed in tank water recently, I made sure to not do them all at once to not kill off a bunch of bacteria.

Q- any dead plants? Anything that could be decaying in there?

A- I have checked all my plants twice over and then again, I always pull off dying roots/leaves. The only creatures that have ever been in here are my axolotls, and the nightcrawlers I fed them. I always took out any uneaten worms I saw.

Q- What’s your PH? GH? KH?

A- PH has always stayed at 7.6, I have never seen it drop or get higher. Current KH is 8°, and GH is 9°


Honestly there’s been so many questions I have answered countless times, but if you have any other ones I don’t mind answering them again, I really just want to figure out where these nitrates are coming from! Please let me know if you have any insight, I am at a total loss here.

 

[Andy Sager]

I won't ask you the same questions over again but....
Have you had a store or other near by hobbyist check your nitrates with a different kit to confirm your results? This is important because I've found that the nitrate reagents can go bad before they are " supposed to" expire.

Have you checked the nitrate level after the water went through your RO system?

Lets start there.

 

[traxolotl]

I won't ask you the same questions over again but....
Have you had a store or other near by hobbyist check your nitrates with a different kit to confirm your results? This is important because I've found that the nitrate reagents can go bad before they are " supposed to" expire.

Have you checked the nitrate level after the water went through your RO system?

Lets start there.

Haha thank you. Yes, I have checked them both just after going through the system and after remineralizing, tests at 0 both ways. There’s a bit of a situation with the owners at my LFS unfortunately so I’m not sure if they are even going to be back open again, but if they are I’m planning on bringing some in to have them test it.

 

[Andy Sager]

Haha thank you. Yes, I have checked them both just after going through the system and after remineralizing, tests at 0 both ways. There’s a bit of a situation with the owners at my LFS unfortunately so I’m not sure if they are even going to be back open again, but if they are I’m planning on bringing some in to have them test it.

Okay, hopefully they do because you always want to get confirmation at least once that your test results are accurate.

Since we presume then that the nitrate is coming from the biological filter, that means that there is a large volume of ammonia being produced. If it's not coming from somewhere else, it's coming from the axolotls. One way to check how much they are producing is to take one and place in a tub or separate tank of new water with just an air stone running for oxygen and then test the water in 12 and 24 hours to see how much ammonia the axolotl is producing. ( Feed as normal.) If at 12 hours you see ammonia between .05 and 1.0, you can remove the axolotl from the test water because you have your answer. It's them causing a large amount of ammonia which is being converted into nitrates which is why you can't keep it down in the tank. What you would need to do is use a product such as a PolyFilter pad or Ammo-sorb or other ones to remove the ammonia BEFORE is goes through the biological filter. OR you can add a corner box filter or other internal filter with these items inside the tank so that you maintain the biological filter in the HOB. This should cut back the amount of ammonia being processed and being converted into nitrate.
ALSO, you will want to monitor the axolotl at least hourly during the test period so that should it start to show signs of stress, you can remove it from the test water into some clean water and test the water for ammonia.

Hope this helps

 

[traxolotl]

Okay, hopefully they do because you always want to get confirmation at least once that your test results are accurate.

Since we presume then that the nitrate is coming from the biological filter, that means that there is a large volume of ammonia being produced. If it's not coming from somewhere else, it's coming from the axolotls. One way to check how much they are producing is to take one and place in a tub or separate tank of new water with just an air stone running for oxygen and then test the water in 12 and 24 hours to see how much ammonia the axolotl is producing. ( Feed as normal.) If at 12 hours you see ammonia between .05 and 1.0, you can remove the axolotl from the test water because you have your answer. It's them causing a large amount of ammonia which is being converted into nitrates which is why you can't keep it down in the tank. What you would need to do is use a product such as a PolyFilter pad or Ammo-sorb or other ones to remove the ammonia BEFORE is goes through the biological filter. OR you can add a corner box filter or other internal filter with these items inside the tank so that you maintain the biological filter in the HOB. This should cut back the amount of ammonia being processed and being converted into nitrate.
ALSO, you will want to monitor the axolotl at least hourly during the test period so that should it start to show signs of stress, you can remove it from the test water into some clean water and test the water for ammonia.

Hope this helps

Unfortunately, there is a flaw in this logic I think.. my nitrate issue has been a thing even when I had my axolots out of the tank for two months while I fishless cycled with ammonium Chloride. I had them tubbed and was changing their water every 12-24 hours and I did actually test the tub water for ammonia to see when I needed to change it. After 12 and 24 hours, the highest I ever saw the ammonia go was .25, maybe a little higher. I haven’t gotten any ammonia-specific filter media though, I’ve been so focused on nitrates I’ve only gotten extra media meant to reduce that, I’ll definitely pick up something like that and see if that helps! That makes total sense too, obviously I want to remove whatever the excess ammonia is before it even processes into nitrates

 

[angiemike6]

Hi I just wonder if you are worrying too much about your nitrate levels. I agree that it is preferable for them to be as low as possible, but they are not as important as Ammonia and nitrites. I have been keeping fish for 30 years. I have a Juwel 40 gallon community tank. I do 35% water changes every week. My fish never get ill and most are more than 10 years in age. I use tap water which the local water company states has nitrate levels of 32 ppm. This would be measured at their end so probably higher when coming out of my tap. I measure it at 40 ppm. When testing my water just prior to a water change it measures between 40-80 ppm. I assume when you talk about colour red that yours are in this ball park also. My ammonia and nitrites always measures 0 ppm. As long as these readings continue at 0 and my fish remain healthy I no longer worry about the nitrate level. I appreciate that some people will disagree with me.

 

[Aiken Drum]

Could i ask what your parameters where like in the tub when you had them in there? Was it easier to maintain water quality in a more controlled environment?

Unless its coming directly from the water, nitrate usually comes from an ammonia source. So that would be your turtles waste, anything thats dead and decaying, uneaten food, and it can leach out of your aquascape. Or more likely a combination of some or all of these. It sounds like this is something you already understand.

I say "usually comes from" because im recalling a friend who was having the same issues you are having. Very knowledgable aquarist, he managed the customer advice team in the aquatics department of a large canadian pet store chain. He finally pinned it down to an artificial decoration that was leaching about 100ppm of straight up nitrate in 24 hours. He thinks it was coming from whatever applied coating was on the decoration. Once it was removed problem solved.

If it where me id remove everything, go bare bottom. Add some UPVC downpipe offcuts as aquascape to give your axolotls some point of interest. You will be able to see any uneaten food and waste, and remove it. See how things go for a while, and if you have no problems gradually add back your aquascape so you can identify whats causing the issue and remove it. It could just be your axolotls are very messy.

 

[Andy Sager]

Hi I just wonder if you are worrying too much about your nitrate levels. I agree that it is preferable for them to be as low as possible, but they are not as important as Ammonia and nitrites. I have been keeping fish for 30 years. I have a Juwel 40 gallon community tank. I do 35% water changes every week. My fish never get ill and most are more than 10 years in age. I use tap water which the local water company states has nitrate levels of 32 ppm. This would be measured at their end so probably higher when coming out of my tap. I measure it at 40 ppm. When testing my water just prior to a water change it measures between 40-80 ppm. I assume when you talk about colour red that yours are in this ball park also. My ammonia and nitrites always measures 0 ppm. As long as these readings continue at 0 and my fish remain healthy I no longer worry about the nitrate level. I appreciate that some people will disagree with me.

If you are doing weekly water changes of a good amount with a tank with low bioload, you probably do not have a nitrate issue however, you should read this from PetMD:
The Potential Dangers of Excess Nitrate Levels
Sure, you've been told so many times that nitrate is harmless. A lot of fishes can tolerate brief exposures of up to 550 ppm. Chronic exposure, on the other hand, can indeed be damaging, even at much lower levels of exposure.

Over time, at just 30 ppm, nitrate can negatively impact cell development in both fishes and invertebrates. Lethargy, poor color, poor immune system and weakened feeding response are all signs of nitrate poisoning.


And this: https://www.vin.com/apputil/content...&catId=124634&id=8896487&ind=428&objTypeID=17

So nitrates are not totally harmless to aquatic life.

 

[Andy Sager]

Unfortunately, there is a flaw in this logic I think.. my nitrate issue has been a thing even when I had my axolots out of the tank for two months while I fishless cycled with ammonium Chloride. I had them tubbed and was changing their water every 12-24 hours and I did actually test the tub water for ammonia to see when I needed to change it. After 12 and 24 hours, the highest I ever saw the ammonia go was .25, maybe a little higher. I haven’t gotten any ammonia-specific filter media though, I’ve been so focused on nitrates I’ve only gotten extra media meant to reduce that, I’ll definitely pick up something like that and see if that helps! That makes total sense too, obviously I want to remove whatever the excess ammonia is before it even processes into nitrates

Okay, I was responding to your point that you had removed the item(s) that were causing nitrate readings even when tested outside the aquarium.
So, you basically did what I was suggesting you test for since the nitrate level was still an issue with those things out of the tank and the axolotls in a separate container.

In Aiken's post, he mentions turtles. What else do you have in the tank besides the Axolotls?

I'm also curious about the Ph of your RO water after remineralizing. High Nitrates usually cause a drop in Ph but 7.6 is not that low unless your starting Ph is say, over 9.0.

 

[Aiken Drum]

In Aiken's post, he mentions turtles. What else do you have in the tank besides the Axolotls?

Sorry. My mistake i originally put turtles instead of axolotls, thought id changed all references to turtles but missed one.

Early morning post, wasnt thinking too clearly l.

 

[Andy Sager]

Sorry. My mistake i originally put turtles instead of axolotls, thought id changed all references to turtles but missed one.

Early morning post, wasnt thinking too clearly l.

Okay, you are forgiven. I thought the OP said just the Axolotls and some worms so the turtle threw me. THEY are real ammonia producers for sure.

 

[Andy Sager]

Unfortunately, there is a flaw in this logic I think.. my nitrate issue has been a thing even when I had my axolots out of the tank for two months while I fishless cycled with ammonium Chloride. I had them tubbed and was changing their water every 12-24 hours and I did actually test the tub water for ammonia to see when I needed to change it. After 12 and 24 hours, the highest I ever saw the ammonia go was .25, maybe a little higher. I haven’t gotten any ammonia-specific filter media though, I’ve been so focused on nitrates I’ve only gotten extra media meant to reduce that, I’ll definitely pick up something like that and see if that helps! That makes total sense too, obviously I want to remove whatever the excess ammonia is before it even processes into nitrates

Doing a little more reading around some other sites with Axolotl keepers, apparently high nitrates are a common problem with them since they do produce a lot of ammonia. ( Why you didn't see that in your experiment is a question. ) Another option I can think of is to also keep plants which are heavy nitrate feeders such as Hornwort or Duck Weed. Coupling these with weekly water changes of at least 25%-30% should help keep the nitrates down.