I need a little help with carbon dosing.

[LilShaz]

I know carbon dosing is a recurrent topic, but I've ran into an issue and I can't find a post that matches my situation and resolved it.

My tank has been set up for almost a year.
It's around 60g, contains a pair of large clownfish which I've had for around 12 years, a handful of snails and a few fungia.
I have a fine (0.5mm-1.0mm) shallow sand bed, and a ceramic scape.
The sump contains a theiling rollermat, bubble magus g7 skimmer, a carbon reactor, and 9 litres of siporax.
My parameters are:
Ammonia 0
Nitrite 0
Nitrate 50-60ppm
Phosphate 0.08
Alk 12.4 dkh (normally 10, but recently had a dosing mishap)
Magnesium 1350ish
Calcium 450

I began carbon dosing in August when my nitrate began to raise from 10-20 to 40ppm. I breed my clownfish and feed heavily to achieve large clutches of eggs, so wasn't surprised my 10% waterchange wasn't keeping up.

Since then my nitrates have gone up to 50-60ppm. I have been upping the dose a little a time, and believe that I have gone as high as I can. If I go higher, I get a bacterial bloom, but my nitrate remains the same.
I've done larger water changes, but nitrate just comes straight back within a couple of days.

I'm stumped, I've never had nitrates this high and I honestly don't know what I'm doing wrong?

 

[vetteguy53081]

While carbon dosing will bring it down, it also has its disadvantages
Give a large container of chemipure elite with has super carbon and gfo . Will bring nitrate down and keep it in check.

 

[HomebroodExotics]

While carbon dosing will bring it down, it also has its disadvantages
Give a large container of chemipure elite with has super carbon and gfo . Will bring nitrate down and keep it in check.

What do you consider the disadvantages?

 

[LilShaz]

It isn't bringing it down, that's the problem.
I do run carbon but I'm not in a position to run gfo, I'm dosing po4 currently.

 

[vetteguy53081]

What do you consider the disadvantages?

Cons of Carbon Dosing:​

• Must Be Started Slowly
• Can Be Dangerous If Overdosed
• Can Strip Tank of Needed Nitrate & Phosphate

 

[King Turkey]

Okay the nitrate comes from somewhere and you need to find the root problem. Generally feeding to much. A dead fish or something dead in the tank will release a ton. So I would recommend feeding less and getting excess food out after feeding. Thank i would highly recommend some more nutrient export. Carbon dosing does help feed the bacteria to have more thus also consuming nitrate phosphate. But is it the right bacteria you are feeding? I would recommend Dr Tim's waste to introduce better bacteria. I would also note a algae scrubber goes a long way and I love mine

 

[Crustaceon]

I know carbon dosing is a recurrent topic, but I've ran into an issue and I can't find a post that matches my situation and resolved it.

My tank has been set up for almost a year.
It's around 60g, contains a pair of large clownfish which I've had for around 12 years, a handful of snails and a few fungia.
I have a fine (0.5mm-1.0mm) shallow sand bed, and a ceramic scape.
The sump contains a theiling rollermat, bubble magus g7 skimmer, a carbon reactor, and 9 litres of siporax.
My parameters are:
Ammonia 0
Nitrite 0
Nitrate 50-60ppm
Phosphate 0.08
Alk 12.4 dkh (normally 10, but recently had a dosing mishap)
Magnesium 1350ish
Calcium 450

I began carbon dosing in August when my nitrate began to raise from 10-20 to 40ppm. I breed my clownfish and feed heavily to achieve large clutches of eggs, so wasn't surprised my 10% waterchange wasn't keeping up.

Since then my nitrates have gone up to 50-60ppm. I have been upping the dose a little a time, and believe that I have gone as high as I can. If I go higher, I get a bacterial bloom, but my nitrate remains the same.
I've done larger water changes, but nitrate just comes straight back within a couple of days.

I'm stumped, I've never had nitrates this high and I honestly don't know what I'm doing wrong?

Phosphates are the limiting factor here. When you dose carbon source, some nitrates and phosphates will be consumed. Now the trick here is if one or the other gets too low, the parameter with the higher number will increase. In your case, phosphates likely went too low for the bacteria to easily utilize, which prevented them from consuming nitrates, which is why you’re seeing the increase in nitrates now. The fix here is to dose a little bit of phosphate solution each day to keep the bacteria happy and consuming nitrate (good call). I’ve never had luck with increased feeding for this task. I wouldn’t be surprised if your tank was consuming .02-.03ppm of phosphate per day and the reason why you’re seeing .08ppm is because it can take a few days for that nitrate consumption to “rebound”. Also, doing water changes while vacuuming the detritus out of the sand bed will help immensely. Try to avoid changing more than 15% per week, just to be safe though.

 

[LilShaz]

Okay the nitrate comes from somewhere and you need to find the root problem. Generally feeding to much. A dead fish or something dead in the tank will release a ton. So I would recommend feeding less and getting excess food out after feeding. Thank i would highly recommend some more nutrient export. Carbon dosing does help feed the bacteria to have more thus also consuming nitrate phosphate. But is it the right bacteria you are feeding? I would recommend Dr Tim's waste to introduce better bacteria. I would also note a algae scrubber goes a long way and I love mine

I'm feeding heavily but it's intentional. The food is all eaten with a couple of minutes but I feed upto four times a day. I'm not wanting to reduce feeding if I can help it, I keep stocking low for this very reason.


I have just ordered a bottle of waste away, so will definitely give it a go.

 

[biophilia]

I'm not sure what the ceramic rockscape you have is like, but one issue you might be running into (especially given your extremely shallow sand bed) is a lack of deep and porous surface area available for the anaerobic bacteria you're feeding with the organic carbon. A lot of ceramic rock is not very porous and, while Siporax certainly can be, it can also clog pretty easily if you have it in a part of your sump that is not getting pre-filtered water (like via a fine filter sock).

 

[LilShaz]

Phosphates are the limiting factor here. When you dose carbon source, some nitrates and phosphates will be consumed. Now the trick here is if one or the other gets too low, the parameter with the higher number will increase. In your case, phosphates likely went too low for the bacteria to easily utilize, which prevented them from consuming nitrates, which is why you’re seeing the increase in nitrates now. The fix here is to dose a little bit of phosphate solution each day to keep the bacteria happy and consuming nitrate (good call). I’ve never had luck with increased feeding for this task. I wouldn’t be surprised if your tank was consuming .02-.03ppm of phosphate per day and the reason why you’re seeing .08ppm is because it can take a few days for that nitrate consumption to “rebound”.

I thought that was the case, but I've been dosing po4 since early December and still not seeing nitrate budge.

How high should I let po4 go? I currently have no algae issues apart from a lime green film on the ceramic.

 

[Nano sapiens]

Not necessarily anything you are doing wrong, just that your feed input is too much for the system/maintenance as it is.

Considering what you are describing, it looks like carbon dosing is not enough to deal with the excess nitrates without having a massive bacterial bloom.

Options:

1. Manually vacuuming the sand bed to remove detritus regularly will help keep nitrates down. Increase your WC's amount and/or frequency. Be patient, can take a few weeks to see significant results (consistency is important here).

2. Have you considered a refugium with Chaeto or an ATS? Either will also reduce PO4, too, so you will likely have to keep PO4 dosing if you wish to maintain 0.08 ppm

3. Another option is a denitrifying sulfur reactor, which shouldn't affect your PO4 level much (if at all). Just a Googled example (not pushing anyone's product here):

https://blog.marinedepot.com/2014/02/korallin-bio-denitrator-ultimate-low.html

 

[LilShaz]

I'm not sure what the ceramic rockscape you have is like, but one issue you might be running into (especially given your extremely shallow sand bed) is a lack of deep and porous surface area available for the anaerobic bacteria you're feeding with the organic carbon. A lot of ceramic rock is not very porous and, while Siporax certainly can be, it can also clog pretty easily if you have it in a part of your sump that is not getting pre-filtered water (like via a fine filter sock).

The ceramic isn't very porous, you are correct. The siporax still looks very clean, the roller mat keeps the sump detritus free, so I do think it's clogged. Half of it is in a high flow area though, so perhaps that's part of the problem?

 

[xshmoox]

I bet your siporax is probably holding a lot of excess nutrients. If you haven’t cleaned that section out I would take a venture that could be your problem. Happened to me when I ran that on a freshwater setup even with a fairly fine filter sock.

 

[Crustaceon]

I thought that was the case, but I've been dosing po4 since early December and still not seeing nitrate budge.

How high should I let po4 go? I currently have no algae issues apart from a lime green film on the ceramic.

For reference, I have a 65g system and went through the same thing, dropping from 50ppm nitrates to a stable 10ppm and .08ppm phosphate. Everyday, I dosed 2ml of vodka and enough seachem phosphorus (not sponsored but if they wanted... ) to raise the level to .15ppm. You want to test each day and adjust accordingly. You want to see slightly hazy water a few hours after dosing. And I never had algae issues as a result. It’s really hard for algae to take root in the middle of a bacteria bloom.

 

[Crustaceon]

I bet your siporax is probably holding a lot of excess nutrients. If you haven’t cleaned that section out I would take a venture that could be your problem. Happened to me when I ran that on a freshwater setup even with a fairly fine filter sock.

OoOo that could be for sure. They can hold quite a bit of detritus. It’s like running bio balls. But with no visible detritus in the sump...maybe not.

 

[LilShaz]

Not necessarily anything you are doing wrong, just that your feed input is too much for the system/maintenance as it is.

Considering what you are describing, it looks like carbon dosing is not enough to deal with the excess nitrates without having a massive bacterial bloom.

Options:

1. Manually vacuuming the sand bed to remove detritus regularly will help keep nitrates down. Be patient, can take a few weeks to see significant results. Consistency is important here.

2. Have you considered a refugium with Chaeto or an ATS? Either will also reduce PO4, too, so you will likely have to keep PO4 dosing if you wish to maintain 0.08 ppm

3. Another option is a denitrifying sulfur reactor, which shouldn't affect your PO4 level much (if at all). Just a Googled example (not pushing anyone's product here):

https://blog.marinedepot.com/2014/02/korallin-bio-denitrator-ultimate-low.html

I already clean the whole sandbed with every water change.
I think the denitrater might be my next step if the waste away doesn't help.
I've never had much luck with keeping algea alive long enough to export anything.

 

[biophilia]

The ceramic isn't very porous, you are correct. The siporax still looks very clean, the roller mat keeps the sump detritus free, so I do think it's clogged. Half of it is in a high flow area though, so perhaps that's part of the problem?

Certainly could be... The Siporax will likely only provide anaerobic conditions if it's not getting a lot of flow pumping through it. Is it possible to move it to a slower-flow area?

A sulfur denitrator has a minor disadvantage in that it will deplete alkalinity so you'll have to keep an eye on that and dose it if you're not already doing so, but it's a good option. There's no harm in using both nitrate reducing methods at the same time if you go that route. If you cut out carbon dosing altogether, beware that it should be done really slowly.

 

[Nano sapiens]

I already clean the whole sandbed with every water change.
I think the denitrater might be my next step if the waste away doesn't help.
I've never had much luck with keeping algea alive long enough to export anything.

Ok, yes, then some type of denitrifing filter could work for you.

 

[xshmoox]

If the sump is indeed clean I would probably try starting out some microbacter7 with light carbon dosing. Really helped get my bacteria population up and dropped my nitrates just about to nothing and my phosphates maintain steady as well. I currently just dose the recommended once a week dose of microbacter7 and am phasing out my carbon dosing as it dropped my nitrates almost to 0 so I am slowly cutting carbon dosing out while slowly actually dosing nitrates to be in the range I want to be.

 

[HomebroodExotics]

If the sump is indeed clean I would probably try starting out some microbacter7 with light carbon dosing. Really helped get my bacteria population up and dropped my nitrates just about to nothing and my phosphates maintain steady as well. I currently just dose the recommended once a week dose of microbacter7 and am phasing out my carbon dosing as it dropped my nitrates almost to 0 so I am slowly cutting carbon dosing out while slowly actually dosing nitrates to be in the range I want to be.

This sounds like a really good plan, I will have to try this technique myself. This seems like the best way to restart things and figure out if maybe the tank was overfed once or if its a continuing problem.