I need a little help with carbon dosing.

[piranhaman00]

Cyano can consume organics, and is a potential concern. It is why I switched from vodka to vinegar: it caused less cyano.

I started with Vinegar and have continued to use it, cyano kept getting worse.

 

[Randy Holmes-Farley Verified Community Expert]

I started with Vinegar and have continued to use it, cyano kept getting worse.

I think it all depends on the strains of bacteria present, and which ones can best consume which organics. In your case, switching to vodka might have helped.

 

[Brew12]

Is it possible you are creating the bacteria needed for nitrate reduction but failing to remove the bacteria at a fast enough rate?
I would try to skim more on the wet side to see if that helps get the nitrate reduction, especially if you have had to dial back on your skimmer input to prevent overflows as you have increased carbon dosing.

 

[piranhaman00]

I think it all depends on the strains of bacteria present, and which ones can best consume which organics. In your case, switching to vodka might have helped.

Possibly, but no alcohol in my house Im fine just keeping up large water changes.

Is it possible you are creating the bacteria needed for nitrate reduction but failing to remove the bacteria at a fast enough rate?
I would try to skim more on the wet side to see if that helps get the nitrate reduction, especially if you have had to dial back on your skimmer input to prevent overflows as you have increased carbon dosing.

You shouldnt have to remove the bacteria to see the reduction though right? The skimmer just pulls the bacteria out, the nitrate was already taken out by the bacteria, similar with chaeto, the nitrate is removed and then you pull out the chaeto.

 

[Brew12]

You shouldnt have to remove the bacteria to see the reduction though right? The skimmer just pulls the bacteria out, the nitrate was already taken out by the bacteria, similar with chaeto, the nitrate is removed and then you pull out the chaeto.

True to an extent, but you do eventually have to remove the biomass you have created. I know if I let me chaeto pack in and self shade the lit parts grow to remove nitrates and the shaded parts break down which releases nitrates back into the water.
I'm not sure if the bacteria produced by carbon dosing will break down back into nitrates in a similar manner, but I suspect it is possible.

 

[piranhaman00]

True to an extent, but you do eventually have to remove the biomass you have created. I know if I let me chaeto pack in and self shade the lit parts grow to remove nitrates and the shaded parts break down which releases nitrates back into the water.
I'm not sure if the bacteria produced by carbon dosing will break down back into nitrates in a similar manner, but I suspect it is possible.

I will agree. But thats probably not happening here. I can see that happening with a system carbon dosing for long while. But idk

 

[Lenett]

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?

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

Careful with denitrifier. Can cause bio filter to crash. Just happened to me. I have 0 po4 & 0 no3 in an established tank.

 

[Randy Holmes-Farley Verified Community Expert]

Careful with denitrifier. Can cause bio filter to crash. Just happened to me. I have 0 po4 & 0 no3 in an established tank.

What do you mean "cause the biofilter to crash"?

 

[TexasTodd]

What test kit are you using? How old is it?
I would try 2-3 brands to check. Would say have local shop test but that sounds like a no given your local lock down.
Or, do an ICP mail off test.....one that tests your RO/DI too. Are you using RO/DI at zero TDS?

 

[LilShaz]

What test kit are you using? How old is it?
I would try 2-3 brands to check. Would say have local shop test but that sounds like a no given your local lock down.
Or, do an ICP mail off test.....one that tests your RO/DI too. Are you using RO/DI at zero TDS?

Nitrate test was performed using salifert (in date)
Po4 was performed by hanna checker.
Both confirmed by three ICPs since August.

RODI is kept 0-1 tds,
Water changes performed with NSW tested at 0.14 nitrate and 0.01 PO4 (via ICP)

 

[LilShaz]

Ughhhh! So I upped the dose from 4.5ml to 5ml yesterday. Last night I cleaned the skimmer cup and noticed it was particularly nasty. Ah ha! I thought I'd cracked it.

This morning however, the skimmer was pulling just cloudy grey water and just got home this evening and the tank is very cloudy again. Dose dropped back down.
No noticeable change in nitrate test but po4 has dropped to 0.03, I'm ordering po4 supplement perhaps this is part my problem.

 

[Randy Holmes-Farley Verified Community Expert]

Ughhhh! So I upped the dose from 4.5ml to 5ml yesterday. Last night I cleaned the skimmer cup and noticed it was particularly nasty. Ah ha! I thought I'd cracked it.

This morning however, the skimmer was pulling just cloudy grey water and just got home this evening and the tank is very cloudy again. Dose dropped back down.
No noticeable change in nitrate test but po4 has dropped to 0.03, I'm ordering po4 supplement perhaps this is part my problem.

The bacteria have to grow somewhere. In many tanks, they grow out of site, down in rocks, etc.

I dosed vinegar into the beginning of my rock filled refugia and never saw any bacteria unless I greatly overdosed, where the water became hazy.

 

[LilShaz]

The bacteria have to grow somewhere. In many tanks, they grow out of site, down in rocks, etc.

I dosed vinegar into the beginning of my rock filled refugia and never saw any bacteria unless I greatly overdosed, where the water became hazy.

I've just moved the dosing outlet into my first sump section with the skimmer and just before the siporax. Do you think adding a remote DSB is the right way to go?

 

[Biglew11]

The .03 ppm phosphate could be an issue, I found.
That was the case in my tank. Carbon dosing wasn't working. I was at zero ppm phosphate. Once I brought phosphate up to around .1 ppm my nitrates started to drop.

 

[LilShaz]

Success!!

Hurrah! finally got a result. All po4 tests below were performed 3 times with Hanna ULR checker, all nitrate tests were performed with a Nyos nitrate kit.

I dosed po4 to 1ppm on the 9th, it was reading 0.7-0.8 24 hours later so I dosed back up to 1ppm. Tested yesterday, down to 0.3-0.5. Today my po4 was 0.02-0.04 and nitrate is reading around 40ppm, down from 50-60ppm.

I'm still going to add a display refugium to help prevent this happening again but I can concentrate on attractive macros instead of focusing on the fast growing species.

Thank you all for your help.

 

[LilShaz]

Still dosing po4. Having to adjust the dosage up at least once a week to keep po4 above 0.03. Now dosing 10mls of zlements po4.

Nitrates are now <25ppm.