Dosing Nitrate to reduce Phosphate

[Randy Holmes-Farley]

I'm not clear on the process or timing in a tank as some N is incorporated in algae tissue at least until its degraded.

In an algae farming operation or an algal turf scrubber application it seems harvesting would limit alk put back . So ,suppose there is no harvesting and no degradation? How does the N move to nitrate, When it's assimilated into tissue is there a reaction affecting alkainity I'm unaware of?

So for the reasons mentioned above, ammonia (not ammonium) conversion into tissue has no impact on alkalinity. Nitrate conversion does add alkalinity, exactly offsetting the loss in alkalinity when ammonia is converted into nitrate.

So a turf scrubber should have no impact on alkalinity, unless one is adding ammonium salts to feed it. If one is relying on fish waste, then that is essentially the algal growth process in exact reverse, so there can be no net gain or loss of alkalinity by going through the loop from algae (fish food) to fish waste and back.

 

[Subsea]

Originally Posted by Subsea
"¦ When N is required I dose with ammonia.
Patrick

I've thought about doing that as it is suggested in a number of studies that organisms take ammonia preferentialy to nitrate, particulary denitrfying heterotropic bacteria .

However, my personal sense of caution proscribes dosing ammonia in significant amounts to a tank with living organisms like fish and inverts which may suffer from ammonia toxicity vs nitrate addtions.
Another difference between nitrate additions and ammonia additions is that ammonia degradation will deplete alkalinity ; the nitrate does not ;it adds bicarbonate alkainity.
For phototrophic nitrogen processing( eg. algae systems) these are the reactions:

Ammonia +CO2+phosphate +water + bicarbonate = algae + O2

Nitrate + Co2 + phosphate + water = algae + O2 + bicarbonate.

Having aroggonite substrate provides for the buffering required to complete this dynamic equilibrium balance. In my case it is a matter of economics.
Patrick

 

[tmz]

I see the issue (two actually) with the powerpoint article conclusion about ammonia.

Equation 1 seems to show that alkalinity is consumed, but that is not a correct conclusion:

16NH4+ + 92 CO2 + HPO42- + 92 H2O + 14 HCO3- → C106H263O110N16P + 106 O2
(1)

That is because they start with ammonium (NH4+), not ammonia (NH3), despite using the exact word "ammonia" in the slide.

If you start with ammonia, the same reaction now reads:

16NH3 + 92 CO2 + HPO42- + 92 H2O + 14 HCO3- + 16 H+ → C106H263O110N16P + 106 O2

So there is no net consumption of alkalinity.

The second issue I have is in the equation right after equation 5:

"The overall removal process can be described as (Ebeling et al., 2005):
NH4+ + 1.83 O2 + 1.97 HCO3- → 0.0244 C5H7O2N + 0.976 NO3- + 2.90 H2O + 1.86 CO2"

Not only does that "overall" process start with ammonium again, it leaves nitrate. Producing the nitrate consumed alkalinity as we know. If you process that nitrate into organics, the alkalinity comes back as we also agreed earlier). That accounts for the two equivalents of alkalinity consumed: one for ammonium issue and one for the nitrate produced.


So I agree that if you dose ammonium, such as ammonium chloride, you will deplete alkalinity by effectively adding a weak acid (the ammonium)

If you dose ammonia, such as ammonium hydroxide (ammonia solution) then alkalinity is not depleted when the nitrogen is converted into organics.

Thankyou,

I see it now. The extra H+ in ammonium vs ammonia.

I thought the paper was pretty tight overall and offers some nice insights into the nitrogen pathways. No wonder you scored summa cum laude on your under graduate work in bioology and chemsitry at Cornell, where Dr. Timmons one of the principal authors is a professor.
I agree with your post 601 as well;just couldn't figure which shell the claimed consumed alkalinity pea was hiding under.

 

[tmz]

Nitrate is not included in a total alkalinity titration.

Those that are include phosphate, borate, carbonate, hydroxide (both free and attached to magnesium), bicarbonate, silicate, and a subtraction of H+.

Sounds like a reef chemistry question of the day to me:thumbsup:

 

[Randy Holmes-Farley]

Sounds like a reef chemistry question of the day to me:thumbsup:

Quite, but I shouldn't mention that here.

 

[Subsea]

Arcane-obscure, requiring secret or mysterious power

Arcane-obscure, requiring secret or mysterious power

I've been off the thread for a while . Glad to see more anecdotal accounts of NO3 dosing vs more arcane tangential discussion on nutrients which drifted away from the central point of the thread.

Tom,
Biology does not work in a vacume. Most everything involving dynamic equilibrium in our aquariums and in the ocean effect each other. To focus on one component only and not consider the big picture, from my point of view, is anal retentive.
I had previously read the three part series that Erick Borneman wrote on "Right to Breath". I reread them to see if I had missed some data that had lifted protein skimmers to the superior level of oxygenating an aquarium that you lift up.

The third paragraph of the introduction sums up my point that skimmers are not an end all method to introduce oxygen or to remove carbon dioxide from the aqquarium water.

"In terms of aquariums, I had always heard that using air bubblers kept tank water oxygenated. I believed it, too, until someone pointed out that the diffusion across an air bubble as it rises to the surface and breaks is so low as to be negligible. It has also been pointed out that most of the gas exchange occurs across the water's surface, and bubbling or any type of surface stirring that mixes the water and creates a greater surface area for gas exchange is far more effective than merely bubbling air into a tank using an airstone and air pump. Many aquarists also have stated that protein skimming dramatically increases "aeration," and that low oxygen levels in highly skimmed reef aquaria are rarely a concern. I was always unsure how much oxygenation occurred in a closed chamber with most of the bubbles being forced to the surface prior to their return to the tank. Still, it made sense, too, that water in contact with such a frothy mix must certainly gain oxygen during its pass through a foam fractionation device. In fact, so much banter exists around this topic that I began to wonder if anyone had really measured reef tanks' oxygen levels, or if any data really existed to support any of the statements commonly made and accepted."

Of course a skimmer aeriates water, so does trickle filters or most importantly agitated surface air interface.
Patrick

 

[Subsea]

I've been off the thread for a while . Glad to see more anecdotal accounts of NO3 dosing vs more arcane tangential discussion on nutrients which drifted away from the central point of the thread.

Tom,
Biology does not work in a vacume. Most everything involving dynamic equilibrium in our aquariums and in the ocean effect each other. To focus on one component only and not consider the big picture, from my point of view, is anal retentive.
I had previously read the three part series that Erick Borneman wrote on "Right to Breath". I reread them to see if I had missed some data that had lifted protein skimmers to the superior level of oxygenating an aquarium that you lift up.

The third paragraph of the introduction sums up my point that skimmers are not an end all method to introduce oxygen or to remove carbon dioxide from the aquarium water.

"In terms of aquariums, I had always heard that using air bubblers kept tank water oxygenated. I believed it, too, until someone pointed out that the diffusion across an air bubble as it rises to the surface and breaks is so low as to be negligible. It has also been pointed out that most of the gas exchange occurs across the water's surface, and bubbling or any type of surface stirring that mixes the water and creates a greater surface area for gas exchange is far more effective than merely bubbling air into a tank using an airstone and air pump. Many aquarists also have stated that protein skimming dramatically increases "aeration," and that low oxygen levels in highly skimmed reef aquaria are rarely a concern. I was always unsure how much oxygenation occurred in a closed chamber with most of the bubbles being forced to the surface prior to their return to the tank. Still, it made sense, too, that water in contact with such a frothy mix must certainly gain oxygen during its pass through a foam fractionation device. In fact, so much banter exists around this topic that I began to wonder if anyone had really measured reef tanks' oxygen levels, or if any data really existed to support any of the statements commonly made and accepted."

Of course a skimmer aeriates water, so does trickle filters or most importantly agitated water surface air interface.
Patrick

 

[Subsea]

I do view leaving out details and dismissing data as less than an exchange of ideas and more as you establishing your superiority on the subject matter.

Patrick

Missed that

I view those things that way but I haven't done any of that. Suffice to say I think you have been looking in a fun house mirror lately.

Tom,
It is true I am having fun with the banter. I find it stimulating. With respect to a fun house mirror, Shakespeare said it more eloquently, "all the world is a stage and all the men and woman are but players".
I seek to learn,
Patrick

 

[reefmutt]

a small anecdote from my current system..
since a leak in my dt has me running a small side system with few fish and few corals, my parameters have been stable at 1-2 ppm nitrate and .14-.18 p.
Up until last week, I had been running aio pellets and cheato with these n and p levels.
Wondering about the cheato's absorption of n and p, I decided to double the amount of aio pellets and remove the cheato to see where the levels would go.. about 10 days later, n is down to .25 and p is up to .3.
In my case, it certainly seems as though the cheato was having a significant effect on p. Unless .25 n is low enough to have limited the bacteria in my system and now p is rising..

As of last night, i have begun additions of vinegar and cano3 and will report back as to how the system reacts..

 

[slavetonet]

a small anecdote from my current system..
since a leak in my dt has me running a small side system with few fish and few corals, my parameters have been stable at 1-2 ppm nitrate and .14-.18 p.
Up until last week, I had been running aio pellets and cheato with these n and p levels.
Wondering about the cheato's absorption of n and p, I decided to double the amount of aio pellets and remove the cheato to see where the levels would go.. about 10 days later, n is down to .25 and p is up to .3.
In my case, it certainly seems as though the cheato was having a significant effect on p. Unless .25 n is low enough to have limited the bacteria in my system and now p is rising..

As of last night, i have begun additions of vinegar and cano3 and will report back as to how the system reacts..

I don't understand why you would need to add vinegar since you have AIO bio pellets.
For my experiment - I have AIO bio pellets and didn't needed to dose vinegar or vodka or sugar for my carbon source.
Phosphate was driven to 0.00 per hanna checker, just by dosing KNO3 for Nitrate. The bacteria do their job utilizing what they needed.

 

[reefmutt]

i can't add anymore biopellets with my current reactor and as they are right now, I'm not quite at 0 n.
Based on the original theory of this thread; when carbon dosing, p becomes uncontrollable when n reaches 0 because the bacteria become nitrated limited.
This is my understanding..
I can't add anymore pellets and my n isn't quite 0.
My intention for adding vinegar is to add to the over all carbon to get n all the way down.
Then, the addition of cano3 is to add the required n, so that the bacteria can start consuming the p.
Is my reasoning faulty?

 

[reefmutt]

Maybe I should just put the cheato back. With the added biopellets, my n should go down to zero and then I'd only need to add cano3..
I've just heard lots of anecdotal evidence of the benefits of using vinegar in conjunction with biopellets..

 

[slavetonet]

Maybe I should just put the cheato back. With the added biopellets, my n should go down to zero and then I'd only need to add cano3..
I've just heard lots of anecdotal evidence of the benefits of using vinegar in conjunction with biopellets..

Please note down your experience in details for all in RC to see.
I would be interested in having different dosing regimes to achieve the same goal.
There are always more way to skin a cat. :lol2:

 

[reefmutt]

I'll test tomorrow and report back.. Before putting the cheato back, I will try this method for a few weeks..

 

[tmz]

Personally, I'd put the caheto back for starters.
I don't use biopellets.btw. I've used vodka and vinegar fo over five years. Your reasoning sounds fine but nitrate isn't the only source of dissolved nitrogen.,so. I don't know if adding it will get the reduction in PO4 you are looking for.

 

[usingthejohn]

Personally, I'd put the caheto back for starters.
I don't use biopellets.btw. I've used vodka and vinegar fo over five years. Your reasoning sounds fine but nitrate isn't the only source of dissolved nitrogen.,so. I don't know if adding it will get the reduction in PO4 you are looking for.

you dose both vinegar and vodka?

Sorry I'm new to carbon dosing and am looking into ways to control nitrates so I'm gathering as much firsthand experience as possible.

 

[tmz]

Both. This thread has a lot of detail as well as anecdotal accounts and may be of interest:

http://www.reefcentral.com/forums/showthread.php?t=2134105&highlight=organic+carbon+dosing

 

[reefmutt]

Tom, thank you for the advice. I will take it.. But in two weeks..
Since I don't have a full blown reef atm, I feel free to experiment. I will continue with my pellets, and vinegar/cano3 for two weeks and see what happens.. After that I will put the cheato back.. By then, I will probably have my DT back and will want to really get down to business

 

[tmz]

Good luck.

 

[reefmutt]

thanks!
here's what I have today..
first, a marked appearance of cyano. not all over but starting.
no3: 1ppm up from .24
po4: .15 down from .3
I will continue with my current dosage of 30ml vinegar (7% acetic acid) and aprox. 1/3 teaspoon cano3 added daily (2 half doses per day)
Ill be interested to see if po4 goes down any more by the weekend.. between .12 and .18 is usually my tank's happy place (and my unhappy place)
I'm shocked at the rapid reduction in biopellets since starting the vinegar, it seems that they have begun to reduce much more quickly..
i might increase the vinegar slightly when i mix a new batch of vin/cano3 this weekend..