Organic carbon dosing

[tmz]

Over the last few months I've received several pms about the increasingly popular techniques for dosing organic carbon via vodka, vinegar, sugar,polymer pellets, etc. I thought it more helpful to respond via this thread to questions about these techniques. So ask away.

First a little backround.

Marine organisms including denitrifying bacteria need: organic carbon,nitogen,phosphorous and oxygen. There is no practical way for hobbyists to measure organic carbon. It is often overlooked but is the third nutrient and the most used. For general perspective marine organisms average about 106 parts carbon to 16 parts nitrogen and only 1 part phosporous.IIRC, natural surface seawater contains: about 1ppm organic carbon ,.2 ppm nitrate and around .02 PO4.

The idea behind dosing organic carbon is to reduce high NO3 and PO4 by feeding the heterotrophic bacteria that consume them more organic carbon and then exporting the bacteria and their organic by products via skimming ,granulated activated carbon and resins like purigen.. The hypothesis is that in a closed system,phosphorous and nitrogen build up to higher levels through feeding, waste, etc. to a point where bacteria reduce the organic carbon creating a limitation due to an organic carbon defficiency, So basically incorporating the inorganic PO4 and NO3, which are removeable by skimming or gac, into organics which can be exported. Some of the bacteria involved are anaerobic and also use the oxygen from NO3 ,leaving N to bond with another N forming N2 gas which bubbles out of the tank and joins the other N2 which makes up about 70% of thee sir around us. The outcome sought is lower inorganic nitrogen and phosporous( ie NO3/NO2 and PO4)

There are pitfalls. Adding too much organic carbon is harmful and it can build up without good export (skimming, activated carbon). Bacterial blooms can also occur with cnsequent oxygen depletion. Since we can't measure teh organic carbon levels or the bacteria it's always a bit of a shot in the dark. Starting slowly and measuring NO3 and PIO4 along the way are prudent precautions.

 

[diverdick]

Tom, I am a little surprised that this thread did not spark interest. IMHO, one of the more "controversial" topics today. Knowing how this group likes to mix it up, I imagined more involvement.

My 2 cents:

I am on week 6 of a solid carbon system. Lets say that I am using "my own brand" of bio-pellet with, what I can only say at this time, outstanding results.

System history: I have ~ 500 gallons of largely stony corals, My nutrient levels, BP (before pellets) were Nitrates - ~ 5 & Phosphates ~ .4 - .6. My intention going into this type of systems is to allow me to feed more "nutrition" to my system vs. limiting feeding to keep "nutrients" low. After 6 weeks of use, I have doubled feeding rates with ZERO affect on nutrient levels. Today, my levels are as follows: Nitrates - 0 (salifert) & Phosphates - .1. The livestock looks very good to boot.

Historically, I have changed water weekly (50 gallons). As of last week, I am pushing it to 2 weeks - 50 gallons.


In a humble attempt to juice this thread/topic

Most Kind Regards.
--Rich

 

[jdoenumber2]

Im just learning still. I am very interested id solid carbon dosing. I just need to decide on a reactor. I am probably going to use the BRS reactor design. Im tagging along.

 

[toddmh]

Is dosing bio pellets and ROX 08 at the same time a bad idea??If so what one is better to use..

 

[tmz]

Thanks Dick.

In keeping with the intent of juicing it up. I like vodka juice with vinegar better than pellets.

No reactor just dump it in or dose it with a doser if you prefer although there may be advantages to anaerobic bacteria with bolus dosing( dosing all at once).

I've been using it for over two years with very good results( NO3 undetectable , PO4 <.05ppm consistently.
I do run a little gfo as well but very little for a 550 g system. While the food we put in a tank carries in nitrogen and phosphorus in roughly a 16N to 1 P ratio, the bacterial activity depletes more N due to consumption at roughly 16 to 1 and the additional N depletion as N2 gas via anaerobic respiration. This often leaves the aquarium with 0 nitrate and some PO4 left over.

I like the vodka/vinegar better than the pellets because I can drink it or use it on a salad. I don't want to manage another reactor either.

Also because of the way anaerobic digestion works.

Pellets are polymers( carbohydrates); they break down to monomers(sugars); monomers break down to ethanol(vodka) and then acetate( vinegar is acetic acid). Corals do use acetate. Each step involves variations in bacterial activity and byproducts with variang effects on the coral's holibont microfuana. I've had trouble with sugar dosing in the past,browning some lps and causing some to recede. Studies have noted increased coral mortality with increased glucose present. So, I don't get any monomers when dosing ethanol or acetic acid, aka vodka or vinegar.

There are several types of pellets and they have advantages and disadvantages but all in all I think vodka and vinegar are safer and at least just as easy to dose and relatively inexpensive. The pellet manufacturers claim all the activity occurs in the reactor so they claim a benefit since no extra carbon or bacterial by products enter the water column. Experience belies that notion, since many have experienced browning, bacterial blooms etc with pellets , just as they do with overdosing direct vodka vinegar or sugar. It's easier to adjust the dose with vodka and vinegar than with pellets so it's more manageable. Some also think the addition of bacteria to the water column directly is a good thing as it enhances support for the food web.
I think it may.

 

[Capt_Cully]

I've read the extensive article from Reefkeeping Magazine on vodka dosing, I highly recommend anyone considering it, read that article (do a search ). There are pitfalls for those with established systems, bacterial blooms, SPS tip bleaching, etc.

Tom, what amounts of vodkee and vinegar are you dosing respectively for your 550 puddle? Was the vinegar a dose a result of an equation, or something you titrated up to?

Way back when, do you recall your starting dose for vodkee? And at what rate did you increase it to achieve your current dose?

Thanks :thumbsup:

 

[low riderr]

how much should one dose when first starting out? say a 300 gal system(240 display with 100 in the basement) does it matter which type of vinager ?is there a prefered time to dose(am/pm)?

 

[nevermind]

I followed this article: http://reefkeeping.com/issues/2008-08/nftt/index.php

Start really low like the article suggested, .1 per 25 gal of water. I don't know if you really have to keep alk at 7 like the article said because I know some people run theirs at like 9+. I keep mines around 7 though cause that's where I ended up at after messing with different levels and I'm afraid to make anymore changes. BTW, don't mess with the alk levels too much like I did, the corals REALLY REALLY do not like it. They seem less tolerant of alk swing with carbon dosing.

Question, is it possible to still overfeed with vodka and vinegar dosing? I am starting to see algae growth on the rocks even thought my PO4 is at 0 (Hanna checker). I was feeding quite a bit of oyster feast every night, could the algae be getting nutrients before they can be taken up by the bacterias?

 

[tmz]

Tom, what amounts of vodkee and vinegar are you dosing respectively for your 550 puddle? Was the vinegar a dose a result of an equation, or something you titrated up to?

Way back when, do you recall your starting dose for vodkee? And at what rate did you increase it to achieve your current dose?

I dose 26ml of vodka and 64 ml of vinegar daily to the 550 gal + puddle. 18 ml of vodka and 64ml of vinegar a couple of hours after lights on and 8ml of vodka at lights out.
I began with 5ml of vodka daily and doubled up weekly until I got to 40 ml which was around the mid point of what most were dosing back then.I adjusted down in response to undetectable NO3 levels and settled in at 34 ml. I was getting some persistent cyano on a sand bed in one frag tank. Some were having success with vinegar as an alternative to vodka in abating cyano. I switched 8ml of vodka to 64 ml of vinegar and the cyano waned so I didn't switch any more. ( Note 80 proof vodka is 60% water and 40% organic carbon,ethanol; white vinegar is 95% water and 5% organic carbon,acetic acid. So it takes 8 ml of vinegar to equal 1 ml of vodka in terms of carbon source).

The article by Nate (Genetics) is solid and cautious. At the time it was written many were bombing their high NO3 tanks with high doses to encourage rapid decreases with tragic results.It became apparent that NO3 reduction proceeded slowly for many(months) leading in some cases to overdosing and the use of sugar with poor results in terms of coral health.
IMO, it is important to reduce your nitrate to reasonable levels say 5ppm before you start and then customize your dose to maintain levels >2ppm . Each tank is idiosyncratic with variables in surface area, biofiltration, feeding regimen ,etc. There is no one dose fits all.

I've never seen any tip burn or other negative effects on sps with alk at a steady 9.6 to 10dkh. I feed 40 fish heavily. The system processes about 2 oz of frozen food per day as well as some flakes and nori. Tip burn or other stn or bleaching may come from a variety of things including: excessive total organic carbon buildup,enhanced water clarity resulting in more intense light ,rapid PO4 reduction enhancing calcification rates without adequate time for corals to adjust tissue growth rates or modify the amounts of PO4 they or their holibont were used to, or diddling with alk levels and so on.
Further on the article , no one I know uses ozone with carbon dosing. GAC and solid skimming and some purigen seem to keep organics under control for me.
A little further on the article. Many now acknowlege the need to use some gfo or another PO4 removal method to maintain very low levels in well fed tanks . As I explained earlier NO3 reduction is likely to exceed PO4 reduction in terms of the proportions you put in with food and the amount processed out by bacterial consumption of N andP and the anerobic respiratory removal of extra N as N2.

 

[tmz]

how much should one dose when first starting out? say a 300 gal system(240 display with 100 in the basement) does it matter which type of vinager ?is there a prefered time to dose(am/pm)?


Plain white vinegar ,no extra flavoring .

Vinegar adds CO2 and will drop ph temporarily and it may be dramatic with a high dose. So I would not dose it during non photosynthetic periods. It is best if using just vinegar to dose it in several increments or drip dose over the course of the photosynthetic period or buffer it with kalk dosing.

Vodka will also ultimately lower ph from Co2 porduced by bacterial activity but gradually allowing for at least some gas off. So bolus dosing vodka during photosynthetic periods works well.

There may be some advantage to dosing organic carbon all at once or in large increments since this may encourage more anaerobic vs aerobic bacterial activity. A bigger feast at once for the heteretrophic bacteria is likely to get them to form mulm and hypoxic areas. It is also likely that larger single doses will permeate surface areas to places where anaerobic activity will ensue.

If using vinegar ,I'd follow the cited vodka article for a start up dosing amount and incremental increases and multiply the vodka values by 8 to get the amount of vinegar to dose at each step.

 

[tmz]

Is dosing bio pellets and ROX 08 at the same time a bad idea??If so what one is better to use..


No it's a great idea,imo. The gac helps remove any excess organics formed in the pellet process. I use rox 24/7 alongside organic carbon dosing ( vodka and vinegar in my case).
Pellets and GAC like rox( granlated activated carbon ) do different things.
Granulated activated carbon primarily removes hydrophobic organic material, some of which holds N and P . GAC can't bind inorganic N and P, ie NO2,NO3 or PO4.
Pellets add organic carbon which is combined with inorganic N and P by heterotrophic bacteria which can along with their organic by products be exported by skimming and gac.

 

[tmz]

Question, is it possible to still overfeed with vodka and vinegar dosing? I am starting to see algae growth on the rocks even thought my PO4 is at 0 (Hanna checker). I was feeding quite a bit of oyster feast every night, could the algae be getting nutrients before they can be taken up by the bacterias?

Sounds like that's what is happening. Maybe you could up the dose or get something to clean the settled food off the rocks.. Organic carbon dosing allows you to feed more but not infinitely more ,in my opinion. At some point with enough food and more dosing to match it , you'll have too many bacteria evident in strings and mats unless Don't forget the bacteria are also believed to be a food source.

 

[GMaquarium]

Very good explanations Tom. This really has been a popular topic, brought up by a number of local hobbyists.

I remember when carbon dosing was viewed as unnatural, however it can't be further from the truth. There is plenty of information available and aquarium experience to learn from. I think biology in general is often overlooked in the hobby. We all know to maintain certain chemical levels for minerals that lead to healthy reefs, so why not nutrient. Just like balancing Ca, Mg and alk we should think of trying to maintain the redfield ratio of c,n,p. This leads to balanced nutrient content in aquariums.

Folks who are new to this should take the time to read up. There are a number of drawbacks and warnings associated with this.

 

[Pny]

This thread is very interesting! (It should have been placed in the advanced discussions instead of down here!) ;-)

What is the difference in having the outlet from a biopellets reactor going directly to the skimmer as recommended today. Does the skimmer take the monomers going out of the biopellets reactor out of the water?

Also, doesnt the introduction of recirculating biopellet reactors add a much better degree of controlling the amount of N&P reduction by reducing the amount of water flowing through the reactor (as long as the reactor throughput per hour is much lower than the total amount of water in the system)?

 

[tmz]

What is the difference in having the outlet from a biopellets reactor going directly to the skimmer as recommended today. Does the skimmer take the monomers going out of the biopellets reactor out of the water?

I think people run them that way in an effort get more of the bacteria and their by products out . Whether it gets all the miscible monomers depends on whether they are amphipathic and attracted to the air /water interface of the foam.



Glad you find the thread intereseting. Thanks

Also, doesnt the introduction of recirculating biopellet reactors add a much better degree of controlling the amount of N&P reduction by reducing the amount of water flowing through the reactor (as long as the reactor throughput per hour is much lower than the total amount of water in the system)?

It's pretty easy and direct to control organic carbon dosing with directly dosed soluble organics . Not sure how much precision one can get regulating flow through a reactor ful of pellets that may degrade at varying rates. When dosing directly you know very precisely how much ethanol and or acetic acid is being dosed without guessing and without any monomers.

 

[Pny]

Using biopellets in a reactor enables you to measure how much PO4 it removes from the water since all filtration occurs in a enclosed environment, the reactor, (assuming that the skimmer takes all bacteria going out from the reactor), instead of having the bacteria all over the place in the aquarium.

Calculating example: If my recirculating biopellets reactor using 2 liters of biopellets media has a throughput of 120 l/h (easy to measure) and the PO4 levels has a difference of 10 ppb P wich equals 0,03066 ppm PO4 (also easy to measure using a Hanna photometer). The reactor will filter out (120*0,03066) = ~3,7 mg/h of PO4 out of the water.

 

[tmz]

Good luck with that.
Monomers are miscible.
Assuming all of the bacteria and byproducts will skim out is a big assumption.
Assuming the reactor flow will remain constant and clog free is also a big assumption. At some point low flow will create anoxic conditions( O oxygen and 0 nitrate) then sulfate reducing bacteria will take over and produce sulfides and toxic and hydrogen sulfide .
The polymer pellets do leach stuff all over the place contrary to early claims. It all moves with the water. It's obvious from the bacterial blooms, cyano and coral issues many experience. Direct control by measure is easierfor most ofus and the compounds in ethanol and acetic acid are simpler and closer to benefical acetate, there are no monomers or polymers there.. I don't wan't or need fermentation, glucose etc in the tank.

Not to mention , the factthat it is much simpler and cheaper.

If the vinegar and /or vodka dose is set properly to match the tank and maintained , bacterial blooms or strings and globs can easily be avoided .,particularly if there is enough surface area in the tank or regufia for them to colonize. Having some bacteria in the tank is not abad thing either imo as many animals I keep feed on bacteria, lot's of microfuana and many corals benefit from them.