Does Carbon dosing result in the sinking of P more so than the export of P

I've been away from reefing forums for a bit and am looking at considering carbon dosing as a mechanism for assisting the management of P as opposed to using GFO, I've had a general read across the forums and was wondering if you could provide your thoughts on a few Q's. The system at the moment is simple Berlin with GFO (although with 2 skimmers).

If I understand correctly the main mechanism that assists in the export of P when carbon dosing is via skimming. essentially
-encouraging the growth of motile hydrophobic bacteria the can then be skimmed from the system
-the increased resulting microcosm mass in the system results in more POM that is then skimmed from the system.

Assuming the above holds some truths, there are a couple of area's i'm looking for thoughts on.

if carbon is indeed the limiting factor, when adding carbon you can not discriminately target a particular bacterial strain, so have little control if the carbon is consumed by water borne (motile as a lose description) or media attached bacteria. In the case of the former, assuming they are hydrophobic, they will probably get skimmed , with the secondary the assimiliation of P will result in an increase of the biomass and essentially rather than being exported the P is essentially going into the 'sink'. So whilst the test kit is showing a lowering of P, is it simply a case that P is being converted from inorganic/ortho to organic/organo and as such just no longer registering on the kit.

Assuming that skimming is selective in terms of the bacteria that it can extract, would the dosing of carbon lead to unskimmable motile bacteria having a favourable position in the longer term? I guess this effect is true of skimming regardless if you use carbon or not? In summary, could skimming essentially lead to the unnatural reduction of the very strains that would assist in export or P, that could be inadvertantly accelerated by Carbon dosing?


Would it essentially be better to setup a carbon tank (CT) that holds a 1/4 of the tank volume with a skimmer attached. Carbon dose the CT for a few days skimming aggressively and then simply cycle the 'cleansed' water from the CT back into display, taking the equivalent amount of display water back into the CT, and then simply repeat the process on a cyclic basis. Would this aid targetting the carbon to just the motile bacteria as opposed to direct dosing into the display? Do any of the current products/potions/vials on the market provide suitable strains that can be innoculated into the CT to increase the effectiveness of such a setup? Does it even make sense considering this or is this paralysis by analysis ;D

 

Perhaps paralysis by analysis?

I think a few of your assumptions are wrong, or atleast the way I'm reading it. That is:

There are several methods of dosing carbon. Assuming solid dosing in the form of pellets, the bacteria is media bound until it is knocked loose by a neighboring pellet, and then fed close to the skimmer (per direction of most biopellets). Assuming liquid dosing, the bacteria could be water borne or media bound, and is most likely both. The water borne is skimmed out.

As for your second assumption in bold, I think that the bacteria ultimately dies off, releases the nutrients back into the water, only to be consumed by another baceria strain. However, one can observe instances of this buildup occurring if too much carbon and nutrients are made available, given the bacterial blooms that some hobbiests observe after dosing too much carbon at once. Over a few days, the bacterial population dies down or is extracted, until balance is once again restored.

Hope this helps?

 

Your are bang on the mark regarding the pellet form. I should have made it clear that the post was principally focusing on the liquid form. What are peoples thoughts on whether all water borne bacteria are skimmable or just the hydrophobic strains? If only a certain type of bacteria are skimmable it makes a huge difference in terms of both the diversity long term and efficiency of the process.

Regarding the second point, the bacteria only die off when some nutrient becomes limited, is it not more likely that what is happening is that the bacteria are consumed/assimilated into higher organisms and simply become a part of the bio-mass? I don't see any evidence that the EXPORT of P via this method is anywhere near as effective as is commonly perceived. The lowering of MEASURABLE P is clearly achievable using this method, but that's not the same as export is it

In essence are you also stating the same aspect, in a large volume of the P is recycled as opposed to exported?

 

I think we are saying the same thing. I'm a bit confused as to what your end goal is. You want to set up a rather complex isolated water filtration system? Why not just try bio pellets or vodka/vinegar dosing? So many people have proved that it works...

 

The end goal is two fold :

-to find an efficient cost effective way of using carbon dosing to EXPORT P in a 600 gallon system to the extent that one doesn't have to use GFO.

-to reduce the amount of water changes by cleansing the water rather than replacing it ( just focusing on the P at this moment and will look at element replacement and other factors later).


I'm linking a few articles that seeded the thoughts of thinking down these lines:-/

Ok, not scientific in the real sense , but some interesting observations none the less

Feature Article: Bacterial Counts in Reef Aquarium Water: Baseline Values and Modulation by Carbon Dosing, Protein Skimming, and Granular Activated Carbon Filtration — Advanced Aquarist | Aquarist Magazine and Blog

impact of skimmer in such systems

Feature Article: Further Studies on Protein Skimmer Performance — Advanced Aquarist | Aquarist Magazine and Blog

part 1 of the AA TOC study

Feature Article: Total Organic Carbon (TOC) and the Reef Aquarium: an Initial Survey, Part I — Advanced Aquarist | Aquarist Magazine and Blog

and part II of the AA TOC study

Feature Article: Total Organic Carbon (TOC) and the Reef Aquarium: an Initial Survey, Part II — Advanced Aquarist | Aquarist Magazine and Blog

Whilst i agree that P can be converted to organic and as such not visible on a test kit, I'm looking at a clean way of maximizing EXPORTING as opposed to both exporting and recycling using the carbon method .I have little evidence but i suspect the ratio of EXPORT: RECYCLE of P using liquid carbon dosing is some where in the region of 3:7. i.e 30% of P is exported and 70% is recycled. Look at any skimmate studies done to date and they kind of point along these lines.

The problem with Carbon dosing in the display is that it is indiscriminate and affects the system a whole, there are of course also benefits.

The method of a CT tank is effectively taking out a 1/4 of the water volume and performing a P dialysis on it and then returning it to the system ( The quicker the better). The potential benefit is that apart from the biofilms that will naturally occur in the CT tank, if it can be innoculated with a suitable strain of skimmable motile hydrophobic bacteria, then the export of P can be enhanced as there are few organisms higher up in the chain that will consume the bacteria (unlike in the display tank). In an isolated system it is also easier to manipulate conditions to make if favorable for P export via skimming as there are fewer variables. It's also easier to induce a quick bloom without the usual associated risks of doing this in a display.

FWIW, I would use my exiting water change container for this purpose, but don't even want to consider the change unless it will provide some benefit, so to an extent the purpose is also to use what is already in place more effectively.

Does this help any ?

 

Hey Reef Clown

very interesting in my opinion

in essence , what you are talking about is a carbon dosing equivelent of a refugium

a refugium holds algaes , bacteria etc , and those assist with the processing of the N and P

in your system, you are giving that role to bacteria to perform prior to the water returning to the main tank

the logic seems good to me

with some reservations

another purpose of carbon dosing to remove N and P, aside from water quality, is also to improve the overal aesthetics of the DT ( algae free, crystal clear water, and colorful corals due etc)

so my reservation is simply that using carbon dosed clean water from the external system and then exchanging that water with water in your DT may not prove efficient enough
you may find that the N and P in the DT are able to out pace the bacteria working remotely

the N and P inputs would be to the DT and only a % of them would be removed when you take some of the water out to be bacterial cleansed remotely

the N and P could also become the limiting factor rather than carbon in the remote system at the end of the day you can only generate as much bacteria as you have nutrients to support in which case you would probably still be carbon dosing your main tank as the unused carbon made their way into the DT when you do the water exchange

but having said that

I would really enjoy you proving your theory is correct and that my reservations are incorrect

I learn nothing from being right
I have an opportunity to learn if I am wrong

Steve

 

Interesting discussion. What about an algae turf scrubber? Do you have a refugium?

 

Very very interesting concept. The points here are also explained exceptionally well in my opinion. I really hope this conversation keeps going, Im enjoying sitting back and reading with my cup of coffee.

 

In such export system, no3 is almost always the limiting factor vs po4, which is why many chose to run gfo or other phosphate export system concurrently with carbon dosing

 

Folks,
thanks for all your input and helping to confirm my thoughts, really appreciated.

confirmed

Whilst GFO is not the cheapest material on the planet, as a P remover it's probably still the most effective for the buck.

Really, thanks for encouraging me not to change my current system, sometimes we tinker too much and need some sense to keep us in check

for the moment i'll leave things as is, but will explore when work allows and i have more time on my hands. I do think there may be some leverage in the method, but it requires more thought and test before even considering:-/

Another interesting concept making an entry in Europe is the Triton Method, it's quite interesting but the makers are not helping themselves at the moment! take a look at the following, i'd be intrested in your thoughts

Triton filtration method. - UltimateReef.com

regards
N