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Very high Nitrates even after major water changes

Joshuawdoggy

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*Edit*
I did test the source water before adding to my tank, and Nitrates are 0 ppm.


I noticed I had very high Nitrates (160ppm) last week. I looked into it as much as I could and yes, I made a mistake by using RO water (Pure, not remineralized.) So this past weekend I went and got mineralized RO water and did 50% water changes. One 50% change on Saturday and one 50% water change on Sunday. I also added Tetra EasyBalance Plus to the tank after both water changes. Nitrates came down to 80 ppm on Sunday after the 2nd water change.
I did a water test today again and I'm sitting at 160ppm Nitrates.
I have 2 fish in the tank right now. The tank is a 55 gallon with a common pleco and a red tail shark. I had pest snails in the tank but they have all died recently. Not a single one is alive in the tank anymore (Alarming, as those things are hard to get rid of). I normally pulled 50 snails out while doing weekly water changes. I do have a 10gallon tank on standby however it is not set up or cycled, so I don't think I can even house my fish in there till I have my 55 gallon water issues sorted...
Water test results (Master test kit):
pH: 7.2
Nitrite: 0 ppm
Nitrate: 160 ppm
Ammonia: 0 ppm

As for the fishes health right now, the pleco has clear stringy poops and doesnt eat that I can tell. The red tail shark seems fine.
 
Last edited:
How large is the common pleco? Because they can become giant, and waste machines.

Photos of the tank/fish perhaps?

What kind of filtration do you have on the tank?
 
Addendum - is it a red-tailed shark, or a red-tailed catfish? Just double checking!

The snails all dying may be a result of the high nitrates, but the fact the loss was sudden, plus the nitrates being so high, makes me wonder whether there was an ammonia spike high enough to kill the snails, but the fish were able to survive it.
 
How large is the common pleco? Because they can become giant, and waste machines.

Photos of the tank/fish perhaps?

What kind of filtration do you have on the tank?
The pleco is about 8". Red tail shark is about 5-6".
Filter is a Aqueon QuietFlow 75 (Rated for an 80 gallon tank). I can get pics later of the tank as well if need be
 
Addendum - is it a red-tailed shark, or a red-tailed catfish? Just double checking!

The snails all dying may be a result of the high nitrates, but the fact the loss was sudden, plus the nitrates being so high, makes me wonder whether there was an ammonia spike high enough to kill the snails, but the fish were able to survive it.
It is a red tail shark.
 
Addendum - is it a red-tailed shark, or a red-tailed catfish? Just double checking!

The snails all dying may be a result of the high nitrates, but the fact the loss was sudden, plus the nitrates being so high, makes me wonder whether there was an ammonia spike high enough to kill the snails, but the fish were able to survive it.
I may have just discovered another mistake perhaps? I use Nutrafin Cycle after every water change (As per directions on bottle). The tank has been established for 1.5 years tho. Maybe this is my issues?
 
I've also just facepalmed and said "DOH!" to myself, because something was niggling at me.

All the snails died, and you said you had a lot of 'em. Even if you're removing as many as you can, that's a huge amount of tiny rotting bodies that the fish are too large to bother with, but that you filter and nitrifying bacteria will have been struggling to convert a lot of ammonia from all those dead snails.

Personally I'd do another large water change, make sure to rinse the filter media (and likely clean the innards/outer parts of the filter too) really well in the removed tank water, then test again, see how levels are. Make sure to give the substrate a really thorough gravel vac too to try to remove as much matter and waste as possible.
 
I may have just discovered another mistake perhaps? I use Nutrafin Cycle after every water change (As per directions on bottle). The tank has been established for 1.5 years tho. Maybe this is my issues?

I'm not familiar with that product I'm afraid, but our chemistry whizz, @Essjay would likely be more help to you there.

It would be handy to get photos of the plec if you're concerned he's not eating, has stringy poop etc. What do you usually feed them, and how long has he not been eating for?

Sorry to be brief in my replies, it's only because I'm pushed for time, but I like to try and help where I can, and there's a puzzle element to this too! So I'd like to find out what's causing the issue as well. :)
 
I've also just facepalmed and said "DOH!" to myself, because something was niggling at me.

All the snails died, and you said you had a lot of 'em. Even if you're removing as many as you can, that's a huge amount of tiny rotting bodies that the fish are too large to bother with, but that you filter and nitrifying bacteria will have been struggling to convert a lot of ammonia from all those dead snails.

Personally I'd do another large water change, make sure to rinse the filter media (and likely clean the innards/outer parts of the filter too) really well in the removed tank water, then test again, see how levels are. Make sure to give the substrate a really thorough gravel vac too to try to remove as much matter and waste as possible.
Yes I should have added more to the OP. I use a gravel vac to do water changes always. and move all decor aside to clean the gravel. All dead snails are removed (altho the eggs are hard to get ALL of them).
I will remove the hob filter and rinse it out tho, that's something I have not done since I started the tank up. Filter pads have been changed maybe 4x in the last year and a half (Once I rinse them in used tank water and the water still over flowes past the pads, I thinks it's time to changed the pads?)
 
Any bacteria which says to add it regulalrly is either not the right bacteria or else they are finding away to sell you something you no longer need. A water change does not reduce the amount of bacteria in a tank.

Whatever is in the Nutrafin is no needed so it will die, that makes ammonia. The fact that you only have nitrate means there is little danger from ammonia or nitrite. however, that level of nitrate is harmful to fish over almost any but a very short term period. Most folks work to top at between20 and 40 ppm on and API style test kit. Lower is better if possible.

Adorabell is partly right. The filter is not struggling, it is working perfectly. the end product of the cycle in a tank with live plants is nitrate. That is what you have. if the bacteria were "struggling" you would test both ammonia and nitrite. The bacteria are making the amount of nitrate they should be of you have excess decaying organic matter. You could go through the proves of trying to clean out the substrate but ti would be messy and a lot of you beneficial bacteria may be in the top inch of the substrate.

I would suggest you just bite the bullet andtrat doing more freqent water changes. over time the organics will all decay and end upo as nitrate which you remove and then the nitrate levels will come down to more normal levels. I would be thinking about doing 1-3 to 1/2 changes about every 2 -3 days. I would start with a couple of back to back huge ones to get the nitrate as far down as possible. Then start the regular changes. If you are staring at 80 you are already too far behind the curve. If you can do an 80% change twice 160 ppm becomes 32 ppm and then even following with just 50% get the tank to 16 ppm. Of course your mileage may vary a bit because hitting the exact %s is not important to get down to the exact 1 %. Close is good enough.

But, if you start at under 20 and stay on top of things, it will be a lot easier.

One last note, The nitrate tests we use are pretty much the least accurate and biggest problem for many of us. The two reagent one form API works like this. The reagents tend to precipitate out of solution. So you need to shake the bottle well before adding the drops. The second bottle is especially bad and may need to be banged on hard surface a couple of times as well. Nitrate is hard to measure. So the way a lot of the test work is they first convert the nitrat to nitrite and then they measure that.
 
I will remove the hob filter and rinse it out tho, that's something I have not done since I started the tank up. Filter pads have been changed maybe 4x in the last year and a half (Once I rinse them in used tank water and the water still over flowes past the pads, I thinks it's time to changed the pads?)

Oh no! Don't throw out and buy new cartridges, those things are a con, a way for filter companies to keep you buying product constantly. I get it, they're corporations, but it's a con that costs hobbyist a lot of money.

Just rinse the cartridges the best you can in old tank water, and order some basic filter sponge and filter floss from Amazon. Replace carbon by removing it from the plastic thingy, then cut some filter sponge to fit, and use that instead. The sponge will last for literal years, doesn't involve throwing away your useful beneficial bacteria (BB) and will save you a fortune. Don't replace all the cartridges with sponge at once, just the most degraded one first, give it a couple of weeks to colonise with BB, then next filter clean, replace a different one, etc. Never need buy cartridges again!

Useful videos about optimising your filters, and he agrees, no sense in throwing away you cash on those cartridge cons.



 
Any bacteria which says to add it regulalrly is either not the right bacteria or else they are finding away to sell you something you no longer need. A water change does not reduce the amount of bacteria in a tank.

Whatever is in the Nutrafin is no needed so it will die, that makes ammonia. The fact that you only have nitrate means there is little danger from ammonia or nitrite. however, that level of nitrate is harmful to fish over almost any but a very short term period. Most folks work to top at between20 and 40 ppm on and API style test kit. Lower is better if possible.

Adorabell is partly right. The filter is not struggling, it is working perfectly. the end product of the cycle in a tank with live plants is nitrate. That is what you have. if the bacteria were "struggling" you would test both ammonia and nitrite. The bacteria are making the amount of nitrate they should be of you have excess decaying organic matter. You could go through the proves of trying to clean out the substrate but ti would be messy and a lot of you beneficial bacteria may be in the top inch of the substrate.

I would suggest you just bite the bullet andtrat doing more freqent water changes. over time the organics will all decay and end upo as nitrate which you remove and then the nitrate levels will come down to more normal levels. I would be thinking about doing 1-3 to 1/2 changes about every 2 -3 days. I would start with a couple of back to back huge ones to get the nitrate as far down as possible. Then start the regular changes. If you are staring at 80 you are already too far behind the curve. If you can do an 80% change twice 160 ppm becomes 32 ppm and then even following with just 50% get the tank to 16 ppm. Of course your mileage may vary a bit because hitting the exact %s is not important to get down to the exact 1 %. Close is good enough.

But, if you start at under 20 and stay on top of things, it will be a lot easier.

One last note, The nitrate tests we use are pretty much the least accurate and biggest problem for many of us. The two reagent one form API works like this. The reagents tend to precipitate out of solution. So you need to shake the bottle well before adding the drops. The second bottle is especially bad and may need to be banged on hard surface a couple of times as well. Nitrate is hard to measure. So the way a lot of the test work is they first convert the nitrat to nitrite and then they measure that.
Thanks very much for the information. I will do 2 80% changes in 4 days then? then regular changes weekly from there? Also there are no live plants in my tank.
 
The high nitrates killed the snails. that are contributing to more nitrates at the moment.

Keep up the water changes and check for ammonia and nitrates as long as one of them builds too much do water changes.

If no ammonia appears, the filter is doing great. You only have to remove as much dead snails and nitrate as you can.

In any Aquarium where there is no plants... I'm sure there no plants in there.

Nitrates will always build up to deadly levels, without appropriate water changes.
 
Oh no! Don't throw out and buy new cartridges, those things are a con, a way for filter companies to keep you buying product constantly. I get it, they're corporations, but it's a con that costs hobbyist a lot of money.

Just rinse the cartridges the best you can in old tank water, and order some basic filter sponge and filter floss from Amazon. Replace carbon by removing it from the plastic thingy, then cut some filter sponge to fit, and use that instead. The sponge will last for literal years, doesn't involve throwing away your useful beneficial bacteria (BB) and will save you a fortune. Don't replace all the cartridges with sponge at once, just the most degraded one first, give it a couple of weeks to colonise with BB, then next filter clean, replace a different one, etc. Never need buy cartridges again!

Useful videos about optimising your filters, and he agrees, no sense in throwing away you cash on those cartridge cons.



Wow, this hobby is a never ending learning experience. Love it. Thanks for the information.
 
Also there are no live plants in my tank.

The filter is not struggling, it is working perfectly. the end product of the cycle in a tank with without live plants is nitrate.
The nitrogen cycle with bacteria converts ammonia to nitrate (oversimplified version). Plants feed directly on ammonia and the only end product is bigger plants, which use even more ammonia (again oversimplified). Having plants will slow the rate of nitrate production over the long run and is highly recommended - the more the better.
An additional benefit is that they provide a safety buffer in the event of a filter failure. With enough live plants you are unlikely to ever experience an ammonia spike, even if the filter fails.
 

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