Does dosing nitrate help reduce phosphate when carbon dosing in your experience?

[reefluvrr]

I am curious about trying to dose Nitrate to help reduce Phosphate when carbon dosing our reef tanks.

Whenever I tried carbon dosing in the past, I became NO3 limited without seeing my PO4 going down to my desired level of around 0.05.
I would then use GFO to help reduce my PO4 level.
(For instance: my NO3 is less than 1ppm and my PO4 is 0.2, so I would use GFO to bring PO4 down to 0.05 to 0.1)

Recently, I listened to BRStv Lou Ekus talk about heterotrophic bacteria efficiently taking up PO4 in our tank through carbon dosing.

This spurned me to want to try carbon dosing again and wanted to know if I should try NO3 dosing or augment with GFO?

I believe BRS Ultra Low Maintenance BRS160 tried dosing NO3 to reduce PO4, but they just could not increase their NO3 level from zero even with dosing.

However, I would like to hear if there are reefers out there that had dosed NO3 and successfully reduced PO4?

Once when you reached a desirable PO4 level: did you have to continue to dose NO3; or did your system balanced out with NO3 to PO4 ratio that you liked without further dosing?

Hopefully this will be helpful to not just me, but others as well.

Thank you.

 

[Scrubber_steve]

I don't believe carbon dosing reduces PO4. Dosing a specific iron product does however, as demonstrated by Glennf, or GFO, algae filtration, .

 

[Randy Holmes-Farley Verified Community Expert]

Carbon dosing in my tank never generated nitrate limitation, even at very high doses. Not sure why.

 

[Dan_P]

I am curious about trying to dose Nitrate to help reduce Phosphate when carbon dosing our reef tanks.

Whenever I tried carbon dosing in the past, I became NO3 limited without seeing my PO4 going down to my desired level of around 0.05.
I would then use GFO to help reduce my PO4 level.
(For instance: my NO3 is less than 1ppm and my PO4 is 0.2, so I would use GFO to bring PO4 down to 0.05 to 0.1)

Recently, I listened to BRStv Lou Ekus talk about heterotrophic bacteria efficiently taking up PO4 in our tank through carbon dosing.

This spurned me to want to try carbon dosing again and wanted to know if I should try NO3 dosing or augment with GFO?

I believe BRS Ultra Low Maintenance BRS160 tried dosing NO3 to reduce PO4, but they just could not increase their NO3 level from zero even with dosing.

However, I would like to hear if there are reefers out there that had dosed NO3 and successfully reduced PO4?

Once when you reached a desirable PO4 level: did you have to continue to dose NO3; or did your system balanced out with NO3 to PO4 ratio that you liked without further dosing?

Hopefully this will be helpful to not just me, but others as well.

Thank you.

I performed carbon dosing experiments with calcium acetate on samples of aquarium water and this little system became phosphate limited, i.e. nitrate consumption stopped until I dosed phosphate. I never performed an experiment where nitrate was limiting, though in principle the same thing should happen.

A funny thing about carbon dosing is that no one has demonstrated whether the decline in nitrates is a result of the assimilation of nitrate by the bacteria, or whether an indirect result of the bacteria assimilating of nitrogen compounds that could be converted to nitrate but are not and that the nitrate is actually removed by algae and other organisms. Carbon dosing might actually shunt the nitrogen supply from nitrate production to heterotrophic biomass production. If the latter mechanism is in play, then dosing amino acids might be a better nitrogen source for bacteria and phosphate reduction, though some cyanobacteria seem to prefer amino acids to nitrate. Carbon and nitrate dosing might drive both bacteria and algae growth, and just maybe, phosphate reduction.

 

[marke]

Whenever I tried carbon dosing in the past, I became NO3 limited without seeing my PO4 going down to my desired level of around 0.05.

I have experienced No3 going to zero due to carbon dosing like yourself. Randy may not have seen this because he suggest going to a 50% maintenance dose once NO3 target is reached. This also happens with systems that have chaeto or algae scrubbers. The redfield ratio says algae and bacteria consume significantly more No3 than Po4. So as we carbon dose we increase our bacteria population which increases our NO3 reduction faster than PO4. What I have done is not back off on carbon dosing when I hit No3 target, but begin nitrate and amino acid dosing. The NO3 dosing will allow for a larger bacteria colony which can now reduce some PO4 while the dosing keeps the No3 stable. The aminos dosing is to overfeed my sps corals without raising PO4 as fast as feeding fish would do. GFo is still being used to keep .03 target. Seems to be an necessary evil for low nutrient sps systems that have fish poop.

Once when you reached a desirable PO4 level: did you have to continue to dose NO3; or did your system balanced out with NO3 to PO4 ratio that you liked without further dosing?

I have found that in our efforts to reach ultra low PO4 targets of .02 to.06 we typically will push N03 levels to zero---so cant stop dosing NO3. If NO3 goes to zero for too long our bacteria population will diminish in size and reduce less NO3. Our sticks will also turn pale due to zero NO3.

 

[reefluvrr]

I have found that in our efforts to reach ultra low PO4 targets of .02 to.06 we typically will push N03 levels to zero---so cant stop dosing NO3. If NO3 goes to zero for too long our bacteria population will diminish in size and reduce less NO3. Our sticks will also turn pale due to zero NO3.

Thank you for sharing your experience.
I am willing to set a doser to dose NO3 daily, however, I am somewhat bummed about hearing the need for GFO still.

I wonder how much uptake does heterotrophic bacteria gets eaten vs having to dose amino acids. Guess I will have to try and find out.

 

[stripe14631]

How did this work out for you? Several months ago I tested my water prior to a new coral shipment and found my NO3 at 4ppm and PO4 at .5 ppm corals all looked good and absolutely no algea on anything, but I thought lowering my phosphate sounded like a good idea. So overnight I went from .5 to .2 with the use of GFO. Since it was my first time using it I had no idea it would work so fast. Then I noticed my biggest torch shriveled up and lost a head. I started connecting the dots so I went about it much slower but every time I try some coral gets upset. So far I've had a alvapora partially bail out 3 heads of a torch die and now my gold hammer is massively receding. I also have a fuge with cheato but it doesn't grow at all. I am now starting to dose NO3 to get my ratios better but my PO4 is also climbing now sitting at .55 I'm at a complete loss and have no idea what to do. I called a reefing expert the other day and he told me imposible your test kit is bad. Since then I've verified that with 2 others.

 

[gbroadbridge]

How did this work out for you? Several months ago I tested my water prior to a new coral shipment and found my NO3 at 4ppm and PO4 at .5 ppm corals all looked good and absolutely no algea on anything, but I thought lowering my phosphate sounded like a good idea. So overnight I went from .5 to .2 with the use of GFO. Since it was my first time using it I had no idea it would work so fast. Then I noticed my biggest torch shriveled up and lost a head. I started connecting the dots so I went about it much slower but every time I try some coral gets upset. So far I've had a alvapora partially bail out 3 heads of a torch die and now my gold hammer is massively receding. I also have a fuge with cheato but it doesn't grow at all. I am now starting to dose NO3 to get my ratios better but my PO4 is also climbing now sitting at .55 I'm at a complete loss and have no idea what to do. I called a reefing expert the other day and he told me imposible your test kit is bad. Since then I've verified that with 2 others.

Carbon dosing has never worked to reduce phosphates for me, although it works well keeping Nitrates down. Been doing it since about 2016.

I still use GFO for phosphate control.

 

[Reef and Dive]

My tank for a long time had phosphate excess after a good nutrient control.
I previously dosed nitrates with carbon.
Now I just remove the excess with GFO.

 

[reefluvrr]

How did this work out for you? Several months ago I tested my water prior to a new coral shipment and found my NO3 at 4ppm and PO4 at .5 ppm corals all looked good and absolutely no algea on anything, but I thought lowering my phosphate sounded like a good idea. So overnight I went from .5 to .2 with the use of GFO.

Whenever I drop my PO4 levels too quickly, I have had corals dying on me.

From my own personal experience, I had difficulty reducing my PO4 levels with just carbon dosing alone.
I have found what works very well for me in reducing either PO4 or NO3 is dosing a bacteria source combined with carbon dosing.

For example, if my PO4 is 0.2 and I want to bring it down to 0.1 or less. For my 40 gallon tank, I can add a bacteria source such as PNS Probio or Dr. Tim's waste away. I would put 30ml of bacteria and 1 to 2 ml of tropic marin bacto balance together in a mixing tube and dump it into my tank. I do not turn off my skimmer. This slowly brings down my PO4 levels from 0.2 to like 0.14 in about 8 hours. If I turn off my skimmer, it works too well. My PO4 levels will go down from 0.2 to 0.05 in about 8 hours.

Again in my experience, if my Nitrogen was limiting, then it was more difficult to bring down PO4. Thus I have dosed N03 to help reduce PO4 if necessary.

At the moment, the problem for me is the yo-yo effect of PO4 going up near the end of the week due to bacteria death, protein skimming, or some other unknown reason. I did not experience this issue in the past...



This is just my experience and I wanted to help share this info in case someone else may find it helpful.

 

[Spare time]

I don't believe carbon dosing reduces PO4. Dosing a specific iron product does however, as demonstrated by Glennf, or GFO, algae filtration, .

By nature it has to remove phosphate/phosphorus. However, most organisms should use more nitrogen in general.

 

[Randy Holmes-Farley Verified Community Expert]

By nature it has to remove phosphate/phosphorus. However, most organisms should use more nitrogen in general.

carbon dosing drives at least two different processes. The ratio of the two processes will certainly vary from tank to tank, but the common report is that carbon dosing has a far bigger effect on nitrate than phosphate.

Here’s why:

1. Denitrification consumes the organic and nitrate and consumes no phosphate.

2. Tissue building by organisms uses both N and P. The ratio used here depends in organism, but is always far higher in N (Akin to the Redfield ratio).

3. When phosphate starts to decline in most tanks, some phosphate bound to calcium carbonate surfaces will be released, partly replacing what was lost. That does not happen with nitrate.

Thus, while #2 lowers both, 1 and 3 cause the nitrate drop to usually be far higher, and some folks detect no change to phosphate.

 

[Spare time]

carbon dosing drives at least two different processes. The ratio of the two processes will certainly vary from tank to tank, but the common report is that carbon dosing has a far bigger effect on nitrate than phosphate.

Here’s why:

1. Denitrification consumes the organic and nitrate and consumes no phosphate.

2. Tissue building by organisms uses both N and P. The ratio used here depends in organism, but is always far higher in N (Akin to the Redfield ratio).

3. When phosphate starts to decline in most tanks, some phosphate bound to calcium carbonate surfaces will be released, partly replacing what was lost. That does not happen with nitrate.

Thus, while #2 lowers both, 1 and 3 cause the nitrate drop to usually be far higher, and some folks detect no change to phosphate.

I was referring to #2 of what you listed. Forgot about number 1, but I am sorta cautious to say its a significant sink for the carbon in modern reef tanks since it requires an environment not frequently promoted in tanks these days.

Do you think denitrification is very prevalent in reef tanks these days? I feel that is requires such a specific environment (and enough of it) to make an impact.

 

[Randy Holmes-Farley Verified Community Expert]

I was referring to #2 of what you listed. Forgot about number 1, but I am sorta cautious to say its a significant sink for the carbon in modern reef tanks since it requires an environment not frequently promoted in tanks these days.

Do you think denitrification is very prevalent in reef tanks these days? I feel that is requires such a specific environment (and enough of it) to make an impact.

I think so, but I do not really know with certainty.

Even biofilms on a bare surface can denitrify.

 

[jmichaelh7]

Dose dosing nitrates decrease phosphates ?

 

[Randy Holmes-Farley Verified Community Expert]

Dose dosing nitrates decrease phosphates ?

That's like asking if you should turn right or left when driving to the grocery store.

In some situations (where nitrate is low and limiting of some significant organism growth in the tank), the answer is yes. Other times, when nitrate is not limiting, the answer is no.

 

[jmichaelh7]

That's like asking if you should turn right or left when driving to the grocery store.

In some situations (where nitrate is low and limiting of some significant organism growth in the tank), the answer is yes. Other times, when nitrate is not limiting, the answer is no.

Thanks for the input