Carbon Dosing having no effect on Nitrates?

[optimisticdingo]

So I've been carbon dosing in my tank for about a little over a month with Tropic Marin Elimi-NP. I started with a Nitrate level of 50ppm and Phosphate of 0.21. I started the Elimi-NP at a dose of 0.1ml per 28 Gallons. I maintained this dose for 2 weeks and then went to 0.2ml/28Gal and finally worked up to a dose of 0.3ml/28Gal.

I've been testing my Nitrate and Phosphate weekly and every time my nitrates stay around 40-50 on my Nyos test kit. My Phosphate read 0.00 tonight on my Hannah checker.

At this point I'm going to be switching to NP Bacto Balance to hopefully allow the phosphate to rise a bit. I don't want to encounter dinos. But why is it that my Phosphate is going down but my Nitrates won't?

In this tank the Nitrates have always been high, even with regular 20% water changes. I'm beginning to wonder if there is something else wrong?

 

[ZoWhat]

With what skimmer are usually exporting excess food and fish poop?

Your skimmer is rated for what total water volume?

 

[ClownSchool]

So I've been carbon dosing in my tank for about a little over a month with Tropic Marin Elimi-NP. I started with a Nitrate level of 50ppm and Phosphate of 0.21. I started the Elimi-NP at a dose of 0.1ml per 28 Gallons. I maintained this dose for 2 weeks and then went to 0.2ml/28Gal and finally worked up to a dose of 0.3ml/28Gal.

I've been testing my Nitrate and Phosphate weekly and every time my nitrates stay around 40-50 on my Nyos test kit. My Phosphate read 0.00 tonight on my Hannah checker.

At this point I'm going to be switching to NP Bacto Balance to hopefully allow the phosphate to rise a bit. I don't want to encounter dinos. But why is it that my Phosphate is going down but my Nitrates won't?

In this tank the Nitrates have always been high, even with regular 20% water changes. I'm beginning to wonder if there is something else wrong?

Check this article out on carbon dosing.

Reefkeeping Magazine - Vinegar Dosing Methodology for the Marine Aquarium

Reefkeeping ...an online magazine for the marine aquarist.

reefkeeping.com

 

[optimisticdingo]

With what skimmer are usually exporting excess food and fish poop?

Your skimmer is rated for what total water volume?

I'm using a Reef Octopus Classic 152-S. It's rated for 90-200 gallons. My system has 110 gallons total. Here is my stock list. Perhaps I'm overstocked.

Lyretail Anthias (Male)
Lyretail Anthias (Female) x3
One Spot Foxface
Purple Firefish
Blue Spotted Jawfish
Lineatus Wrasse (Male)
Midas Blenny
Black Blenny
Coral Beauty Angelfish
Purple Sea Urchin
Red Linkia Starfish

 

[Spieg]

Nitrate and Phosphate are a package deal with regards to carbon dosing. You need to have some Phosphate available of you wont reduce Nitrate.

 

[optimisticdingo]

Nitrate and Phosphate are a package deal with regards to carbon dosing. You need to have some Phosphate available of you wont reduce Nitrate.

Ok but this doesn't explain why my phosphates have been reduced due to carbon dosing, but my Nitrates haven't moved.

 

[Spieg]

Ok but this doesn't explain why my phosphates have been reduced due to carbon dosing, but my Nitrates haven't moved.

You likely did export some Nitrate (until Phosphate went to zero) although not enough to overcome what you have introduced.

 

[MaxTremors]

Ok but this doesn't explain why my phosphates have been reduced due to carbon dosing, but my Nitrates haven't moved.

You’re assuming it’s the carbon dosing that lowered your phosphates. In general m, carbon dosing doesn’t lower phosphates by all that much. The bacteria need some phosphates in order to consume nitrates, but it’s not an effective treatment to lower phosphates. I would look to other causes for why your phosphates went down. But now that you’re phosphate limited, carbon dosing won’t be able to consume nitrates.

 

[optimisticdingo]

You’re assuming it’s the carbon dosing that lowered your phosphates. In general m, carbon dosing doesn’t lower phosphates by all that much. The bacteria need some phosphates in order to consume nitrates, but it’s not an effective treatment to lower phosphates. I would look to other causes for why your phosphates went down. But now that you’re phosphate limited, carbon dosing won’t be able to consume nitrates.

The only thing that has changed though is the carbon dosing. I've been feeding the same amount as I always do

 

[Randy Holmes-Farley Verified Community Expert]

Ok but this doesn't explain why my phosphates have been reduced due to carbon dosing, but my Nitrates haven't moved.

I do not think that is likely. While that may be what you observed, it didn't happen just from carbon dosing.

 

[optimisticdingo]

I do not think that is likely. While that may be what you observed, it didn't happen just from carbon dosing.

I suppose there's a bit more algae in the tank than there was previously. Would that lower phosphates without affecting nitrate though? Also, apart from feeding I'm not sure what would be causing my nitrates to be so high all the time and not also have high Phosphate?

 

[ReefGeezer]

The only thing that has changed though is the carbon dosing. I've been feeding the same amount as I always do

Correlation doesn't mean causation. The bacteria that carbon dosing encourages and the organic compounds formed due to the extra carbon availability are going to bind nitrate at a much higher rate than phosphate. The number is somewhat dependent on the organisms and compounds created and then exported, but it should be safe to say that the process will bind 10X more nitrate than it does phosphate.
It is hard to see drops in nitrate at high levels. A 50ppm reading on a lot of kits could be much higher but below the level of the next higher reading on the test kit color comparator. You may have decreased nitrate and not been able to see a color change.

 

[optimisticdingo]

Correlation doesn't mean causation. The bacteria that carbon dosing encourages and the organic compounds formed due to the extra carbon availability are going to bind nitrate at a much higher rate than phosphate. The number is somewhat dependent on the organisms and compounds created and then exported, but it should be safe to say that the process will bind 10X more nitrate than it does phosphate.
It is hard to see drops in nitrate at high levels. A 50ppm reading on a lot of kits could be much higher but below the level of the next higher reading on the test kit color comparator. You may have decreased nitrate and not been able to see a color change.

My test kit ranges from 3ppm to 160ppm. It seems like every time I test it's somewhere between 65 and 40ppm which is why I'm assuming 50ppm. You could be right though

 

[ReefGeezer]

If your P was .21 and dropped 0, it could be that you dropped N maybe 4ppm. Once the P was gone, the N would practically stop dropping. It is very hard to deal with high N using only carbon dosing for that reason. You might think about doing a bunch of BIG water changes to get the level down below 10ppm and then starting to carbon. BTW... vinegar or vodka works just as well as the hobby brands and is much cheaper.

 

[Hans-Werner]

I've been testing my Nitrate and Phosphate weekly and every time my nitrates stay around 40-50 on my Nyos test kit. My Phosphate read 0.00 tonight on my Hannah checker.

Hello,
I am doing the R & D at Tropic Marin and we have seen more often nitrate drop and phosphate staying at the same level. Did you get a continuous drop in phosphate concentration or did it seem to drop suddenly? If it seemed a sudden drop please repeat the test. Sometimes it is only a bad test, a powder pillow which is not sealed properly etc..

If the phosphate concentration has really dropped, please check the water for nitrite. Sometimes when using organic carbon or sulfur for nitrate reduction, nitrate is only reduced to the level of nitrite, and even low nitrite concentrations may give false-high results with the nitrate test.

In fact all colorimetric nitrate-tests ultimately measure nitrite after partial reduction of nitrate.

 

[optimisticdingo]

Hello,
I am doing the R & D at Tropic Marin and we have seen more often nitrate drop and phosphate staying at the same level. Did you get a continuous drop in phosphate concentration or did it seem to drop suddenly? If it seemed a sudden drop please repeat the test. Sometimes it is only a bad test, a powder pillow which is not sealed properly etc..

If the phosphate concentration has really dropped, please check the water for nitrite. Sometimes when using organic carbon or sulfur for nitrate reduction, nitrate is only reduced to the level of nitrite, and even low nitrite concentrations may give false-high results with the nitrate test.

In fact all colorimetric nitrate-tests ultimately measure nitrite after partial reduction of nitrate.

When I tested Phosphate a week ago it was 0.1ppm. this week it was zero. It steadily dropped over time. I'll test for Nitrite today and see if I get any results.

 

[Randy Holmes-Farley Verified Community Expert]

Maybe there is a phosphate testing problem?

 

[optimisticdingo]

Maybe there is a phosphate testing problem?

I'll redo the phosphate test this afternoon as well. However, I conducted the test the same way that I normally do. I use the Hannah Phosphate checker and make sure to shake the cuvette for a solid 2 minutes on a timer before placing it into the checker.

I use 1 cuvette for the test and I make sure to clean the cuvette with a microfiber cloth before placing it into the checker wether that be zeroing out the checker or doing the test once reagent is added.

 

[Randy Holmes-Farley Verified Community Expert]

I'll redo the phosphate test this afternoon as well. However, I conducted the test the same way that I normally do. I use the Hannah Phosphate checker and make sure to shake the cuvette for a solid 2 minutes on a timer before placing it into the checker.

I use 1 cuvette for the test and I make sure to clean the cuvette with a microfiber cloth before placing it into the checker wether that be zeroing out the checker or doing the test once reagent is added.

Faulty tests do not always indicate a faulty use of them. Sometimes a scratch on a cuvette, reagents getting old, etc can give poor results.

Also, many phosphate tests will be hard pressed to distinguish readings that vary by less than 0.05 ppm.

The Hanna 713, for example, can read a true 0.04 ppm as anything between 0.00 and 0.08 ppm phosphate (according to Hanna).

 

[ClownSchool]

I do not think that is likely. While that may be what you observed, it didn't happen just from carbon dosing.

Also, according to the article I posted above - if I’m remembering it correctly - carbon dosing effects nitrates versus phosphates 16 to 1, respectively. So, you should see a much greater reduction in nitrates from dosing.