Carbon limited reef?

[JohDwyer]

I have never been able to get a phosphate reading. 0.00 on Hana ULR. I was told to add NeoPhos, which I did. But I still measure 0.00 on multiple tests. The NeoPhos bottle said that If the phosphate doesn't increase, and the nitrate is stable, it means I'm carbon limited and need to add BioFuel which is a carbon source. My Nitrates are between 3 and 5ppm. Im worried that If I add a carbon source my nitrates will bottom out. What is the relationship between Carbon, phosphate, and nitrogen? How can adding carbon result in increased phosphate? This seems counterintuitive from what I've read about carbon dosing.

 

[captainbeardly]

How many fish do you have? How many times a day do you feed? Do you run gfo?

 

[MGarrison]

I was dosing Phosphates. How long have you been dosing? It can take a while for it to start to show up. You want to go slow to avoid a sudden spike.
Also I have switch from liquid phosphates to Spirulina powder and ReefRoids.

From the Moonshiner's handbook:
Phospates (Now Spirulina Powder)
If Po4 is desired to be increased, I recommend the use of Spirulina super food to be used. This is organic addition of Po4, and gentle use will show effects after a few days. I recommend usually to supplement 1-2 Mini spoons as from Red Sea Pro Test kits per 100G per day and adjust after a few days. Please bear in mind that tanks which were starving from Po4 for a longer time, usually consume a lot more in the first few days until saturated and levels begin to raise, so watch out for this sudden effect to avoid Po4 spikes at the end.

 

[taricha]

The NeoPhos bottle said that If the phosphate doesn't increase, and the nitrate is stable, it means I'm carbon limited and need to add BioFuel which is a carbon source.

Did it really say that?
What a strange thing to say. No idea how PO4 being hard to raise means carbon dosing is needed.

 

[a.t.t.r]

Did it really say that?
What a strange thing to say. No idea how PO4 being hard to raise means carbon dosing is needed.

Seems like it would be the opposite. Higher carbon more bio uptake of po4.. kinda why people vodka dose

 

[MGarrison]

Did it really say that?
What a strange thing to say. No idea how PO4 being hard to raise means carbon dosing is needed.

ATI has the best explain of the relationship that I have see so far.

Nutrition C:N:P » ATI-Aquaristik

 

[JohDwyer]

How many fish do you have? How many times a day do you feed? Do you run gfo?

I feed once a day, reef roids every other day, no gfo. I have a 40 gallon reef with a clown goby, melanarus wrasse, bangaii cardinal, juvenile YWG, and a clown.

 

[JohDwyer]

I was dosing Phosphates. How long have you been dosing? It can take a while for it to start to show up. You want to go slow to avoid a sudden spike.
Also I have switch from liquid phosphates to Spirulina powder and ReefRoids.

From the Moonshiner's handbook:
Phospates (Now Spirulina Powder)
If Po4 is desired to be increased, I recommend the use of Spirulina super food to be used. This is organic addition of Po4, and gentle use will show effects after a few days. I recommend usually to supplement 1-2 Mini spoons as from Red Sea Pro Test kits per 100G per day and adjust after a few days. Please bear in mind that tanks which were starving from Po4 for a longer time, usually consume a lot more in the first few days until saturated and levels begin to raise, so watch out for this sudden effect to avoid Po4 spikes at the end.

So based on the equation on the bottle, I dosed enough to achieve 0.02. I dosed 3 nights in a row. 24 hours after each dose I tested and got a reading of 0.00. I even checked the test by adding a drop of NeoPhos to a test tube to ensure the reagent was working properly. All tests were run on a Hana checker ULR and backed up with salifert. I use reef roids every other day and always have. My micromussa lords do terribly if I don't feed them. I run nothing but a skimmer and some ceramic media and dose ALL FOR REEF. Its a very simple set up but I've had great results with softies and LPS and all sps except across.

 

[Nano sapiens]

I have never been able to get a phosphate reading. 0.00 on Hana ULR. I was told to add NeoPhos, which I did. But I still measure 0.00 on multiple tests. The NeoPhos bottle said that If the phosphate doesn't increase, and the nitrate is stable, it means I'm carbon limited and need to add BioFuel which is a carbon source. My Nitrates are between 3 and 5ppm. Im worried that If I add a carbon source my nitrates will bottom out. What is the relationship between Carbon, phosphate, and nitrogen? How can adding carbon result in increased phosphate? This seems counterintuitive from what I've read about carbon dosing.

​

Brightwell Neophos Instructions:​

Instructions and Guidelines​

Shake product well before using. Do not overdose. Results will be most significant when the system is being dosed with MICROBACTER7 on a daily or bi-daily basis.


1. Using accurate test kits or calibrated digital testing devices, determine phosphate and nitrate concentrations in system. It is assumed that the phosphate concentration in the system is below detectable limits for the testing method being employed.


2. Apply NEOPHOS as directed below to attain a phosphate concentration of ~0.02 ppm.


3. Allow 24-hours to elapse; re-test nitrate and phosphate concentrations. If concentrations remain unchanged, then the system is likely carbon-limited. Dose with REEF BIOFUEL at the rate of 1-ml per 25 US-gallons and allow 24-hours to elapse, then re-test phosphate and nitrate concentrations. Continue daily dosing with REEF BIOFUEL until phosphate or nitrate concentrations begin to decrease, indicating that the rate of carbon input to the system
matches the rate of phosphorus- or nitrogen-input, respectively.


4. If nitrate concentration decreases without addition of REEF BIOFUEL or use of KATALYST, phosphate concentration in the system will decrease. Continue dosing with NEOPHOS to maintain phosphate concentration
of ~0.01 - 0.02 ppm until nitrate concentration falls to within desired range (suggested 3 - 5 ppm). Thereafter, dose with NEOPHOS as required to maintain desired phosphate and nitrate concentrations.


Note: If at any time, dosing with NEOPHOS results in a prolonged increase of phosphate concentration without gradual decrease as nitrate is taken up, system is likely carbon-limited (remedied by the application of REEF BIOFUEL or KATALYST to the system). Refer to Steps 3 and 4, or to our website (NEOPHOS "Technical" page).

Basically, what they are saying is consistent with carbon dosing theory/practice as I understand it. There is always an inherent risk when carbon dosing of bottoming out nutrients, so that's why it's mostly recommended for advanced reefers.

All I can say from prior experience is that you need to take it REALLY slow and test often to make sure you aren't reducing nutrients too far and/or too fast. It certainly does the job and in my case (lower dose vinegar) it took NO3 down to ~2 ppm, but it also took PO4 too low as I too normally can't get a PO4 reading (sorry SPS ). Currently, I have elevated NO3 from daily feeding a type of NPS and so have implemented a very low carbon dosing regimen using vinegar (acetic acid) and an increase in the usage of high phosphate foods (Green superfoods which are mainly spirulina algae and high phosphate flake food) over other types of low phosphate foods.

 

[Nano sapiens]

So based on the equation on the bottle, I dosed enough to achieve 0.02. I dosed 3 nights in a row. 24 hours after each dose I tested and got a reading of 0.00. I even checked the test by adding a drop of NeoPhos to a test tube to ensure the reagent was working properly. All tests were run on a Hana checker ULR and backed up with salifert. I use reef roids every other day and always have. My micromussa lords do terribly if I don't feed them. I run nothing but a skimmer and some ceramic media and dose ALL FOR REEF. Its a very simple set up but I've had great results with softies and LPS and all sps except across.

So, you are not carbon limited since your PO4 dropped during the 3 days to '0':

From Brightwell: 3. Allow 24-hours to elapse; re-test nitrate and phosphate concentrations. If concentrations remain unchanged, then the system is likely carbon-limited.

IME/IMO, in a mature system you really have nothing to worry about with your numbers ('0' PO4 and '3-5' NO3) IF you are regularly feeding the aquarium and the animals are healthy with good coloration. Just because PO4 doesn't register on a test kit from the water column, that doesn't necessarily mean that the system isn't getting enough PO4. It just means that the phosphate you are adding is being very rapidly assimilated (lots of hungry mouths, coral, algae, bacteria, etc.).

Here's a small '0 read' (Salifert) PO4 system that's run that way for 13 years:

 

[JohDwyer]

So, you are not carbon limited since your PO4 dropped during the 3 days to '0':

From Brightwell: 3. Allow 24-hours to elapse; re-test nitrate and phosphate concentrations. If concentrations remain unchanged, then the system is likely carbon-limited.

IME/IMO, in a mature system you really have nothing to worry about with your numbers ('0' PO4 and '3-5' NO3) IF you are regularly feeding the aquarium and the animals are healthy with good coloration. Just because PO4 doesn't register on a test kit from the water column, that doesn't necessarily mean that the system isn't getting enough PO4. It just means that the phosphate you are adding is being very rapidly assimilated (lots of hungry mouths, coral, algae, bacteria, etc.).

Here's a small '0 read' (Salifert) PO4 system that's run that way for 13 years:

I think you misunderstood what I was trying to convey. I added enough to achieve 0.02 but that amount of phosphate did not actually measure 0.02. It measured 0.00. So according to the instructions on the product, I am carbon limited (whatever that means). I was fine with the 0.00 reading until I started to add and lose acropora. So this 0.00 reading needs to be corrected unless I give up on acros, which id rather not do.

 

[JohDwyer]

​

Brightwell Neophos Instructions:​

Instructions and Guidelines​

Shake product well before using. Do not overdose. Results will be most significant when the system is being dosed with MICROBACTER7 on a daily or bi-daily basis.


1. Using accurate test kits or calibrated digital testing devices, determine phosphate and nitrate concentrations in system. It is assumed that the phosphate concentration in the system is below detectable limits for the testing method being employed.


2. Apply NEOPHOS as directed below to attain a phosphate concentration of ~0.02 ppm.


3. Allow 24-hours to elapse; re-test nitrate and phosphate concentrations. If concentrations remain unchanged, then the system is likely carbon-limited. Dose with REEF BIOFUEL at the rate of 1-ml per 25 US-gallons and allow 24-hours to elapse, then re-test phosphate and nitrate concentrations. Continue daily dosing with REEF BIOFUEL until phosphate or nitrate concentrations begin to decrease, indicating that the rate of carbon input to the system
matches the rate of phosphorus- or nitrogen-input, respectively.


4. If nitrate concentration decreases without addition of REEF BIOFUEL or use of KATALYST, phosphate concentration in the system will decrease. Continue dosing with NEOPHOS to maintain phosphate concentration
of ~0.01 - 0.02 ppm until nitrate concentration falls to within desired range (suggested 3 - 5 ppm). Thereafter, dose with NEOPHOS as required to maintain desired phosphate and nitrate concentrations.


Note: If at any time, dosing with NEOPHOS results in a prolonged increase of phosphate concentration without gradual decrease as nitrate is taken up, system is likely carbon-limited (remedied by the application of REEF BIOFUEL or KATALYST to the system). Refer to Steps 3 and 4, or to our website (NEOPHOS "Technical" page).

Basically, what they are saying is consistent with carbon dosing theory/practice as I understand it. There is always an inherent risk when carbon dosing of bottoming out nutrients, so that's why it's mostly recommended for advanced reefers.

All I can say from prior experience is that you need to take it REALLY slow and test often to make sure you aren't reducing nutrients too far and/or too fast. It certainly does the job and in my case (lower dose vinegar) it took NO3 down to ~2 ppm, but it also took PO4 too low as I too normally can't get a PO4 reading (sorry SPS ). Currently, I have elevated NO3 from daily feeding a type of NPS and so have implemented a very low carbon dosing regimen using vinegar (acetic acid) and an increase in the usage of high phosphate foods (Green superfoods which are mainly spirulina algae and high phosphate flake food) over other types of low phosphate foods.

I appreciate you looking up the instructions and your response. What I still don't understand is; if my phosphate is unchanged from 0.00, why on earth would I add carbon which should reduce both nitrate and phosphate?

 

[ariellemermaid]

I appreciate you looking up the instructions and your response. What I still don't understand is; if my phosphate is unchanged from 0.00, why on earth would I add carbon which should reduce both nitrate and phosphate?

I think maybe because you skipped step 2 if I’m reading the instructions correctly. Step 2: dose until you get 0.02. You never achieved that.

Then in step 3 (and I think clarified in the “note”) what it’s saying is give your tank 24 hours to use/decrease nitrate and phosphate (from a level of 0.02). If nitrate and phosphate remain the same 24 hours after being at 0.02 then they’re not being used up, which then might mean the tank is “carbon-limited.”

Then step 4 comes in. If both decrease everything is good, keep dosing as you are.

I don’t think it has anything to do with struggling to get up to 0.02 in the first place. As someone said above, this means it’s getting used up or removed which isn’t a bad thing. Just keep going with step 2. Once you get to 0.02 what happens in the next 24 hours will determine what you do.

Disclaimer: never dosed any of this stuff. Just interpreting the instructions above.

 

[ariellemermaid]

Also, are you testing the PO4 right after adding it or waiting? The instructions don’t specify but also don’t say to wait either. Just says dose to 0.02 then in the next step see what happens to the 0.02 24 hours later. So I would assume it’s intending you add it, let it mix, test to confirm the level, then retest in 24 hours to see what the new level/usage is.

I think these directions could have been written more clearly, but I would just follow the steps, in order, word for word, and don’t assume anything.

 

[captainbeardly]

Also, are you testing the PO4 right after adding it or waiting? The instructions don’t specify but also don’t say to wait either. Just says dose to 0.02 then in the next step see what happens to the 0.02 24 hours later. So I would assume it’s intending you add it, let it mix, test to confirm the level, then retest in 24 hours to see what the new level/usage is.

I think these directions could have been written more clearly, but I would just follow the steps, in order, word for word, and don’t assume anything.

It says in the instructions to allow 24 hrs to elapse then retest

 

[ariellemermaid]

It says in the instructions to allow 24 hrs to elapse then retest

Yes to retest in step 3. But step 2 says dose to 0.02 first (which to be sure, would require either faith you got the dose right or an immediate post mix test to confirm). Then you can move on to step 3 at 24 hours. That’s how I read those directions.

When the OP says he can’t get to 0.02 I wonder if he’s dosing and not testing then moving onto step 3 and testing at 24 hours and wondering why it’s 0 and not 0.02. In this case, it very well could have been 0.02 at dosing and getting fully consumed by 24 hours. Which would confirm PO4 is being consumed and the tank isn’t “carbon-limited” which was the question. The instructions want you to dose to a level and see what gets consumed in 24 hours. He says he’s never seen anything above 0 when dosing what should be 0.02 and that’s the only explanation that makes sense to me. It doesn’t say it should be 0.02 after 24 hours, in fact, it clearly says it should be less and that is what he’s finding.

 

[captainbeardly]

Yes to retest in step 3. But step 2 says dose to 0.02 first (which to be sure, would require either faith you got the dose right or an immediate post mix test to confirm). Then you can move on to step 3 at 24 hours. That’s how I read those directions.

When the OP says he can’t get to 0.02 I wonder if he’s dosing and not testing then moving onto step 3 and testing at 24 hours and wondering why it’s 0 and not 0.02. In this case, it very well could have been 0.02 at dosing and getting fully consumed by 24 hours. Which would confirm PO4 is being consumed and the tank isn’t “carbon-limited” which was the question. The instructions want you to dose to a level and see what gets consumed in 24 hours. He says he’s never seen anything above 0 when dosing what should be 0.02 and that’s the only explanation that makes sense to me. It doesn’t say it should be 0.02 after 24 hours, in fact, it clearly says it should be less and that is what he’s finding

Yes to retest in step 3. But step 2 says dose to 0.02 first (which to be sure, would require either faith you got the dose right or an immediate post mix test to confirm). Then you can move on to step 3 at 24 hours. That’s how I read those directions.

When the OP says he can’t get to 0.02 I wonder if he’s dosing and not testing then moving onto step 3 and testing at 24 hours and wondering why it’s 0 and not 0.02. In this case, it very well could have been 0.02 at dosing and getting fully consumed by 24 hours. Which would confirm PO4 is being consumed and the tank isn’t “carbon-limited” which was the question. The instructions want you to dose to a level and see what gets consumed in 24 hours. He says he’s never seen anything above 0 when dosing what should be 0.02 and that’s the only explanation that makes sense to me. It doesn’t say it should be 0.02 after 24 hours, in fact, it clearly says it should be less and that is what he’s finding

What I would do then is add neophos to make it 0.02. Wait 12 hours then retest and see what it says. Then wait the 24hrs and retest both phosphate and nitrate. If both went down that means his bacteria is doing what it should. I myself have to dose nitrate twice a day, once in the morning and once at night to keep my phosphate between 0.05-0.08 and nitrates stay right at 5. I do use both neophos and neonitro. In his case he may have to dose phosphate more than once a day to keep his levels up.

 

[JohDwyer]

Also, are you testing the PO4 right after adding it or waiting? The instructions don’t specify but also don’t say to wait either. Just says dose to 0.02 then in the next step see what happens to the 0.02 24 hours later. So I would assume it’s intending you add it, let it mix, test to confirm the level, then retest in 24 hours to see what the new level/usage is.

I think these directions could have been written more clearly, but I would just follow the steps, in order, word for word, and don’t assume anything.

So are you saying I should just continue adding the recommended 2.5mL per day until I get a reading of 0.02? I'm on day 4 of that and it makes me nervous adding so much phosphate into the tank. If the equation on the bottle is correct, this is enough phosphate to be at 0.08 over 4 days but has gotten me nowhere. Which would mean there is some form of phosphate sink absorbing everything I'm dosing. I just added today's dose roughly an hour ago and I tested phosphate and it is still 0.00. The only thing I found that could be the issue other than 2 faulty tests from two separate companies, which seems unlikely, is "In a low phosphate situation, some portion of the added phosphate will bind to calcium carbonate surfaces, lowering the actual amount in the water."

 

[captainbeardly]

So are you saying I should just continue adding the recommended 2.5mL per day until I get a reading of 0.02? I'm on day 4 of that and it makes me nervous adding so much phosphate into the tank. If the equation on the bottle is correct, this is enough phosphate to be at 0.08 over 4 days but has gotten me nowhere. Which would mean there is some form of phosphate sink absorbing everything I'm dosing. I just added today's dose roughly an hour ago and I tested phosphate and it is still 0.00. The only thing I found that could be the issue other than 2 faulty tests from two separate companies, which seems unlikely, is "In a low phosphate situation, some portion of the added phosphate will bind to calcium carbonate surfaces, lowering the actual amount in the water."

I may have missed what test kit are you using? I use Hanna low range kit. So the exact dosing calculator is your water volume x ppm increase x 3.785.
example
35 gallons x 0.02 x 3.785 = ML to add

 

[captainbeardly]

I may have missed what test kit are you using? I use Hanna low range kit. So the exact dosing calculator is your water volume x ppm increase x 3.785.
example
35 gallons x 0.02 x 3.785 = ML to add

So add 2.6 ml of Neophos to tank would be how much I would to my tank and it’ll raise my NO4 by 0.02