Skimmerless: who's doing it? pros and cons

[Subsea]

Advanced Aquaria Feature Article in March 2011

Feature Article: Bacterial Counts in Reef Aquarium Water: Baseline Values and Modulation by Carbon Dosing, Protein Skimming, and Granular Activated Carbon Filtration
By Ken S. Feldman, Allison A. Place, Sanjay Joshi, Gary White
What are the bacteria populations in the water column of reef tanks, and how does that value compare with bacterial counts in authentic reef water? Does carbon dosing indeed increase water column bacteria populations (i.e., is growth carbon limited)? Does mechanical filtration (protein skimming and/or GAC filtration) actually remove bacteria from the water column, and if so, how much? Ken, Allison, Sanjay, and Gary's in-depth article puts these questions to the test.


CONTENTS
1. Introduction
1.1 The goal of our study - testing the validity of the Carbon Dosing hypothesis
1.2 Bacteria: A general introduction
Bacterial Physiology
Bacterial Surface Charge and Protein Skimming
1.3 Bacterial life processes
Bacterial Metabolism
Bacterial Growth
Bacterial Nutrients
Manipulating Bacterial Growth
The Coral Holobiont
"Probiotic" Application of Bacteria
1.4 Counting bacteria in the water column
2. Experimental Approach
2.1 General experimental
2.2 Control experiments and bacterial contamination
2.3 Data workup
3. Results and Discussion
3.1 Baseline bacteria counts
3.2 Carbon dosing (planned and inadvertent) - How does it affect water column bacteria levels?
3.3 Bacteria removal via mechanical filtration - how effective?
4. Conclusions
5. Acknowledgments
6. References
Departments of Chemistry (Ken S. Feldman, Allison A. Place) and Industrial and Manufacturing Engineering (Sanjay Joshi), The Pennsylvania State University, University Park, Pennsylvania 16802,

In the introduction, results from previous scientific articles about TOC are summarized and referenced below.
Patrick

Our earlier research on the topic of carbon nutrient levels in marine aquaria (Feldman, 2008; Feldman, 2009; Feldman, 2010) has provided experimental documentation for four conclusions that impact on TOC management in our reef tanks:

Reef aquaria utilizing active filtration (GAC, skimming) maintain equilibrium TOC levels within the range found on healthy tropical reefs.
Protein skimming (i.e., bubbles) is not very effective at removing TOC from aquarium water, depleting typical reef tank water of only ~ 20 - 35% of the post-feeding TOC present.
GAC filtration is quite effective at stripping reef tank water of its TOC load, removing 60 - 85% of the TOC present.
And, quite intriguingly, the natural biological filtration, which starts with bacteria and other microbes, is remarkable in its capacity to remediate reef tank water of TOC, easily removing 50% or more of the post-feeding TOC increase in tank water.
Conclusions (2) and (3) describe the consequences of mechanical filtration on TOC levels, but the 4th conclusion emphasizes the importance of the "hidden" part of the remediation equation, bacterial predation, for gaining an understanding of the dynamics of carbon commerce in our aquaria. In fact, this observation, coupled with the advent of Carbon Dosing strategies for nutrient export, led to a new series of questions regarding the perhaps pivotal role of bacteria, or at least skimmable water column bacteria, in successful reef aquarium husbandry.

For my natural systems I focus on the fourth conclusion of this earlier study. It emphasises the hidden part of the dynamic processes, bacteria predation. The predation of bacteria happens on many levels. I focus on filter feeders and corals which are active consumers of bacteria. Lowering nitrate and phosphate is not an issue in my extablished system. My inexpensive test kit can not find any levels of these two nutrients but I know that they are there by the growth of macro algae. I have sent samples off to be tested at agriculture test labarotories with levels that were not dected at the level of their test procedures. Even without this documentation, I know that nitrates and phosphate are in the tank. Otherwise corals, macro algae and bacteria populations would all decline.
I am all for contributing to the healthy growth of bacteria populations. Without healthy bacteria populations, the Martians in War of the Worlds would not have been defeated and earth as we know it would cease to exist. While the reference to the Martians is an attempt at satire, the second part to the sentence is that healthy bacteria populations are mandatory for biological life to exist on earth. Considering that nitrate and phosphate reduction is not required, I do not need to export the bacteria which reduces nitrate and phosphate. For my purposes, protein skimming is counter productive. The Feldman experiments support Paul's statement that bacteria in the water column will reproduce as fast as the skimmer removes them. His last statement at the end of the scientific paper questions the long term health of corals in our captive ecosystems due to skewed populations effecting diversity. He ends with the conclusion that more test are required.

In researching articles of carbon dosing, initial comments say that protein skimming is required and not to carbon dose with DSB in place. Melvin's Reef has an article on his successes with carbon dosing with DSB methods. Considering that the barameter that establishes the right dose are reducing nitrate and phosphate readings, I proceed with,caution. In my quest to provide food for bacteria diversity, I will start with 0.1 ml of 5% vinegar and observe results for the next 60 days.
I seek to learn.
Patrick

Scot,
In reading the article about details on testing controls, it was pointed out that with the use of Red Sea salt, a significant increase in bacteria populations were noted. This was due to the nature of some salt coming from evaporative beds producing dried crystals. Considering that bacteria can exist in this dehydrated salt crystals, your concern about bacteria diversity introduction has another method to correct the concern.

 

[tmz]

I agree with you that holiobont bacteria would not be removed by skimming because they are not water borne as with bacteria existing in biofilms.
I would like to know what water borne bacteria are being skimmed out other then heterotrophs that are caught passing to and from biofilms etc.
Do you know of any studies involving studies of skimmate for bacteria content?

No I don't. The Penn state work doesn't deal with it either.

 

[tmz]

In researching articles of carbon dosing, initial comments say that protein skimming is required and not to carbon dose with DSB in place. Melvin's Reef has an article on his successes with carbon dosing with DSB methods. Considering that the barameter that establishes the right dose are reducing nitrate and phosphate readings, I proceed with,caution. In my quest to provide food for bacteria diversity, I will start with 0.1 ml of 5% vinegar and observe results for the next 60 days.


Patrick ,

Those early concerns regarding DSBs were about the potential for the extra organic carbon to go into anoxic areas and fuel sulfate reducing bacteria which produce hydrogen sulfide as a by product.
I can tell you I have a 7 inch deep sand bed in one of my refugiums and have dosed moderate vodka and vinager amounts for over 5 years without any of that.

The skimmer recommendation is for aeration( the bacteria use oxygen and produce CO2) and for bacteria harvesting.

I agree GAC is generally noted as more efficient for TOC reduction than a skimmer, even more so when GAC and ozone are used togethr as suggesterd in a study cited in one of Randy's articles ( >20% reduction with skimming; around 35% with GAC ,and: about 70% with GAC and skimming , IIRC .
However, the bacteria will likely grow on the activated carbon and clog it up some ,so you need to monitor that if you are counting on GAC for organics reduction when dosing organic carbon.. The skimmer physically removes some of them continuosly ; the GAC does not unless you change it out. I'm also not certain those percentages apply when specific bacteria are being exported ;since, GAC and sikimming have variable affinities for different organics

Do you mean .1ml of vodka for the 65 gallon or .1ml per gallon ? The later should be a sfe dose. FWIW I dose the equivalent of around .6ml per gallon of water volume in the skimmed system. I have been dosing only 3 ml to 30 g breeder that is unskimmed but uses GAC.

 

[tmz]

I'm interested in starting carbon dosing, but vinegar doesn't work for me due to my already low pH. I stopped all Lime water dosing in order to bring my Dkh down from 13, and thus far my pH remains stable at 8.0 with a low of 7.97. Since the bacteria produced from organic carbon increases CO2, I presume that would affect my pH as well, but how much?

The vinegar is about the same as any other carbon source in terms of pH reduction if you does it slowly. In volume it will drop pH right away but make most of it up in a couple of hours as the process moves along. In the end whether it's vodka vinegar or some other source the pH drop relates to the bacterial activity which realtes to the the total amount of organic carbon you provide. In my case I lost 0.15 pH. I made it up with CO2 scrubbers. Current pH runs 8.15 to 8.35 daily swing.

 

[tmz]

I agree with you that holiobont bacteria would not be removed by skimming because they are not water borne as with bacteria existing in biofilms

Biofilms break up and some are exported or eaten. The facultative heterotrophs grow fast enough to make up the difference if you feed them though. IME.

 

[Subsea]

In researching articles of carbon dosing, initial comments say that protein skimming is required and not to carbon dose with DSB in place. Melvin's Reef has an article on his successes with carbon dosing with DSB methods. Considering that the barameter that establishes the right dose are reducing nitrate and phosphate readings, I proceed with,caution. In my quest to provide food for bacteria diversity, I will start with 0.1 ml of 5% vinegar and observe results for the next 60 days.


Patrick ,

Those early concerns regarding DSBs were about the potential for the extra organic carbon to go into anoxic areas and fuel sulfate reducing bacteria which produce hydrogen sulfide as a by product.
I can tell you I have a 7 inch deep sand bed in one of my refugiums and have dosed moderate vodka and vinager amounts for over 5 years without any of that.

The skimmer recommendation is for aeration( the bacteria use oxygen and produce CO2) and for bacteria harvesting.

I agree GAC is generally noted as more efficient for TOC reduction than a skimmer, even more so when GAC and ozone are used togethr as suggesterd in a study cited in one of Randy's articles ( >20% reduction with skimming; around 35% with GAC ,and: about 70% with GAC and skimming , IIRC .
However, the bacteria will likely grow on the activated carbon and clog it up some ,so you need to monitor that if you are counting on GAC for organics reduction when dosing organic carbon.. The skimmer physically removes some of them continuosly ; the GAC does not unless you change it out. I'm also not certain those percentages apply when specific bacteria are being exported ;since, GAC and sikimming have variable affinities for different organics

Do you mean .1ml of vodka for the 65 gallon or .1ml per gallon ? The later should be a sfe dose. FWIW I dose the equivalent of around .6ml per gallon of water volume in the skimmed system. I have been dosing only 3 ml to 30 g breeder that is unskimmed but uses GAC.

Tom,
One recipe for vinegar dosing recommended 0.1 ml of 5% acetic acid for every 25G. With 75G DT and 30G refugium I calculate 0.4 ml. That amount seems insignificant to me. How can such a small amount of 5% vinegar effect pH? For organics reduction from the system, I will export macro algae as compost for my tomatoes. For TOC reduction, I will use GAC. For gas exchange, I will use wet/dry filter with bioballs.

In your above post, you said vodka? Because I am a recovering alcoholic, I did not plan to keep vodka in the house. I know that vodka is heavy on the sugar, that was why I asked about the white sugar. Nevertheless, I will begin the process with 5% acetic acid at a dose of 0.4 ml. I will replace GAC weekly or biweekly if required.

Time of dosing was recommended early in photo cycle. What implication does this have? With photosynthesis, oxygen will be given off and carbon dioxide consumed. Is the bacteria response to carbon source so quick that their use of oxygen and expelling CO2, synchronized with the opposite cycle of photosynthesis?
Patrick

 

[Subsea]

Scot,
Due to the complexities of identifying different bacteria strain, I doubt that we will find out specific bacteria types removed in skimmate.

An indirect destructive test can more easily be done to analyze the the skimmate for inorganic compounds removed. Sprung & Delbric, in Reef Aquarium, Volum 3 refer to one test on page 309.

"A, study by Japanese hobbyist on skimmate removed from a reef aquarium showed that this material can also contain calcium and magnesium (Mizuno 2000). One gram of thick sludge-like skimmer effluent was air dried, then dissolved in nitric acid and hydrogen peroxide and measured using an atomic absorption/flame emission spectrometer. Mizuno found approximately 202 mg/g of calcium, 21.2 mg/g of magnesium, 5.63 mg/g of phosphate and 30.3 mg/g of iron"

 

[Randy Holmes-Farley]

One recipe for vinegar dosing recommended 0.1 ml of 5% acetic acid for every 25G. With 75G DT and 30G refugium I calculate 0.4 ml. That amount seems insignificant to me. How can such a small amount of 5% vinegar effect pH?

That is an extremely low dose. I've dosed more than 1 mL per gallon of total system volume for an extended period, but concluded it was too high. I currently dose about 0.3 mL per gallon total system volume.

As to the pH effect, 1 mL of distilled white vinegar per gallon of aquarium water will achieve an initial pH drop of about 0.3 pH units (depends, of course, on the tank alkalinity and also the starting pH).

 

[tmz]

Tom,
One recipe for vinegar dosing recommended 0.1 ml of 5% acetic acid for every 25G. With 75G DT and 30G refugium I calculate 0.4 ml. That amount seems insignificant to me. How can such a small amount of 5% vinegar effect pH?

Not much pH effect short or long term at that level. Not much extra organic C either. I think that may be a very/overly safe start up recommendation coupled with an amp up plan. You can probably go higher and faste; though, a smallish dose may be what you want since NO3 and PO4 are low.

I can dose 80ml of vinegar to 650 gallons with only a small downward twitch( < 0.1) in pH when it's dosed. It recovers in an hour or so. More than that needs to be spread out to avoid a significant downward pH spike,IME With a dose of vodka and vinegar equivalent to about .6ml vniegar per gallon ( 36 ml 80 proof vodka an 80 ml vineagar).

For clarification ,any organic carbon source will increase bacterial activity which produces CO2 which lowers the pH. Acetic acid does it quickly at the star but in the end any source gets about the same pH variation. With my dose( a dose of vodka and vinegar equivalent to about .6ml vniegar per gallon ( 36 ml 80 proof vodka an 80 ml vineagar).
in my sytem , pH dropped 0.15. I got it back to 8.15 /8.35 dialy wing with a CO2 scrubber.

For organics reduction from the system, I will export macro algae as compost for my tomatoes. For TOC reduction, I will use GAC. For gas exchange, I will use wet/dry filter with bioballs.

In your above post, you said vodka? Because I am a recovering alcoholic, I did not plan to keep vodka in the house. I know that vodka is heavy on the sugar, that was why I asked about the white sugar. Nevertheless, I will begin the process with 5% acetic acid at a dose of 0.4 ml. I will replace GAC weekly or biweekly if required.

I meant to say vinegar/ oops. Vinegar is fine at low volume or dosed slowly at high volume.

Plain vodka has no sugar; it's just ethanol and distilled water. The carbohydrates and sugars have already been fermented to the ethanol.



Time of dosing was recommended early in photo cycle. What implication does this have? With photosynthesis, oxygen will be given off and carbon dioxide consumed. Is the bacteria response to carbon source so quick that their use of oxygen and expelling CO2, synchronized with the opposite cycle of photosynthesis?

Vinegar dumps a lot of H / CO2 when initially dosed quickly. These bacteria do seem grow quickly. Dosing during photosynthetic periods helps mitigate the pH effect and the potential oxygen depletion.
Patrick

 

[Subsea]

Distinguished gentlemen,
Thank you for the guidance. I will dose 25ml of 5% vinegar in my 100G system. If nothing changes after 30 days. I will ramp up to 40ml for the next 30 days.
Patrick

 

[Imperator_]

So yesterday I dosed 20ml of 5% vinegar, an hour later my DT was looking like someone poured milk in it! My pH before the dose was 8.0, it quickly dropped to 7.9 within 45 minutes of dosing. Within a few hours, my pH had dropped to 7.5...it eventually stabilized at 7.7... I swear I didn't over dose! I double checked myself many times.Originally I wanted to try this without the use of a skimmer, but with the bacterial bloom and the ph drop I freaked out, so I immediately put the skimmer in the sump and turned on my UV sterilizer. That was late last night, today as I was at work I so my ph slowly climb from a 7.7 to a now 8.1. When it got home today from work my tank looked super clear and pristine, the bacterial bloom was gone, Still have the UVS running and the skimmer, my corals look very happy and my pH keeps climbing. Note that I am not dosing lime water, was my pH problem a lack of a skimmer/aeration? I haven't had a skimmer in the sump since I bought it about 18 months ago and used it for 48hrs then changed my mind and put it aside. BTW, is keeping my UVS on counteracting the benefits of carbon dosing? What did I do wrong yesterday as far a the vinegar dosing? -my system is about 150g so 20ml was too much? Now I don't know what to do.. Should I turn my UVS off? Should I remove the skimmer or keep it? Should I lower my dosage for
Next time? My apex graphs look crazy!!!

 

[tmz]

Distinguished gentlemen,
Thank you for the guidance. I will dose 25ml of 5% vinegar in my 100G system. If nothing changes after 30 days. I will ramp up to 40ml for the next 30 days.
Patrick

You are welcome.
It's hard to prescribe a starating point since tanks are diferent. 25 ml might be ok but might be a little high for your aquarium at start up . I'd probably start at 10 ml or less to lessen the chance of a bacterial bloom. At 25 ml if you choose that amount be sure to spread out the dose over at least several hours, during the photsynthetic period.

Good luck.

 

[tmz]

So yesterday I dosed 20ml of 5% vinegar, an hour later my DT was looking like someone poured milk in it! My pH before the dose was 8.0, it quickly dropped to 7.9 within 45 minutes of dosing. Within a few hours, my pH had dropped to 7.5...it eventually stabilized at 7.7... I swear I didn't over dose! I double checked myself many times.Originally I wanted to try this without the use of a skimmer, but with the bacterial bloom and the ph drop I freaked out, so I immediately put the skimmer in the sump and turned on my UV sterilizer. That was late last night, today as I was at work I so my ph slowly climb from a 7.7 to a now 8.1. When it got home today from work my tank looked super clear and pristine, the bacterial bloom was gone,

Well the 20ml was it seems too much for a start up dose for your tank as evident in the bacterial bloom particularly since you dosed it all at once. Vinegar in volume should be spread out over time to allow the excess CO2 from it to equlibrate with the air .

Still have the UVS running and the skimmer, my corals look very happy and my pH keeps climbing. Note that I am not dosing lime water, was my pH problem a lack of a skimmer/aeration?

I'd guess the skimmer enhanced gas exchange and CO2 is blowing off more quickly.

I haven't had a skimmer in the sump since I bought it about 18 months ago and used it for 48hrs then changed my mind and put it aside. BTW, is keeping my UVS on counteracting the benefits of carbon dosing? What did I do wrong yesterday as far a the vinegar dosing? -my system is about 150g so 20ml was too much? Now I don't know what to do.. Should I turn my UVS off? Should I remove the skimmer or keep it? Should I lower my dosage for

I'd personally, cut the dose in half and amp up from that new baseline slowly. Dosing the vinegar at the 20ml level all at once caused the pH drop initially , then the bacterial bloom pushed it again and further. Since the bloom is gone , I 'd cut off the uv. I'd keep the skimmer in play. Monitor the alk and pH to help decide when to restart calcium hydoxide (kalk) dosing.


Next time? My apex graphs look crazy!!!

 

[Imperator_]

Thank you tom! All this information is really helpful.






Jaime

 

[Randy Holmes-Farley]

So yesterday I dosed 20ml of 5% vinegar, an hour later my DT was looking like someone poured milk in it!

If you had started real slow, that wouldn't have happened, but I'm not necessarily of the opinion that slower is necessarily better.

After a while, more and more of the bacteria will eventually be on rocks and such, but it does have to grow somewhere.

Where are you dosing int eh system? Do you have a refugium? Dosing just upstream of it may help keep the bacteria more localized.

 

[Subsea]

+10 on what Randy said.

I dosed twice the vinegar to water ration that you did. No clody water. While I do not have a protein skimmer, I have a surface skimmer that gravity feeds to the refugium. Vinegar was dosed into this overflow box. This mixed water & vinegar poured over the wet dry compartment with bioballs and entered the mud and macro algae filter. Considering the maturity of a 12 year old system, it is not an equal comparison but the principal is the same.

In Feldman's research there were two things that he concluded about biological filtration and bacteria predatation.

"Fueling bacteria growth via carbon dosing is medigated by bacteria preditation. This is the beginning of the food chain and it feeds our corals and other filter feeders. Thus the highly dynamic nature of bacteria populations is the hidden component in the process. From a differrent prospective, the bacteria populations in a reef tank seems to act as a buffer to help dissapate the otherwise potential serious negative consequences of tank polluttion via rapid carbon addittion."

"GAC filtration is quite effective at stripping reef tank water of its TOC load, removing
60-85% of the TOC present."

"The natural biological filter which starts with bacteria and other microbes, is remarkable in its capacity to remediate reef tank water of TOC, easily removing 50% or more of post feeding TOC in tank water."

With respect to GAC, it would be good to change it frequently, particularly during the start up of carbon dosing. Consider small amounts changed bi weekly.
Patrick

 

[Imperator_]

If you had started real slow, that wouldn't have happened, but I'm not necessarily of the opinion that slower is necessarily better.

After a while, more and more of the bacteria will eventually be on rocks and such, but it does have to grow somewhere.

Where are you dosing int eh system? Do you have a refugium? Dosing just upstream of it may help keep the bacteria more localized.

So should I drip dose it next time? I could use an IV bag and hang it over the sump and set it to drip over the period of an hour, but for that I would have to mix it with RODI water.... perhaps the algae bloom was inevitable either way? I dosed it in the sump. My sump is 35g and from there the flow leads to my refugium which then leads to another mini sump where the skimmer is located and the return to main tank. I don't have live rock in the sump, should I add live rock to the sump for more surface area, I have heard mixed opinions on that before. My refugium doesn't have that much room for live rock it's only a 20L .

 

[Imperator_]

So should I drip dose it next time? I could use an IV bag and hang it over the sump and set it to drip over the period of an hour, but for that I would have to mix it with RODI water.... perhaps the algae bloom was inevitable either way? I dosed it in the sump. My sump is 35g and from there the flow leads to my refugium which then leads to another mini sump where the skimmer is located and the return to main tank. I don't have live rock in the sump, should I add live rock to the sump for more surface area, I have heard mixed opinions on that before. My refugium doesn't have that much room for live rock it's only a 20L .

I meant to say- bacterial bloom. Also, since I had an unexpected bloom, how long should I wait until the next dosage?

 

[Randy Holmes-Farley]

By start slow I meant low dose then ramp up each day.

I wouldn't do much different than you are and I'd keep dosing.

If you get another bloom, then maybe cut back a bit before ramping up.

FWIW, the bloom doesn't hurt anything and maybe feds certain filter feeding creatures.

 

[Imperator_]

By start slow I meant low dose then ramp up each day.

I wouldn't do much different than you are and I'd keep dosing.

If you get another bloom, then maybe cut back a bit before ramping up.

FWIW, the bloom doesn't hurt anything and maybe feds certain filter feeding creatures.

Great! I will resume dosing then. Btw, my dkh has dropped to 10 and my calcium is about 480, and my pH is still stable at 8.1. I created a GAC "cannon", it's kind of like a potato cannon, but with bags of carbon inside, at 600g/h flow through it... it's keeping the water super clean!

On another subject, has anyone ever used the product Ich Attack by Kordon. I'm bringing this up because I noticed some of you talking about the efficiency of UV sterilizer in removing Ich. I had an Ich outbreak about a year back and due to the fact that at the time I did not have a QT big enough to house all of my fish in for 10 weeks, I gave the UVS a try and it certainly did not work. I lost a beautiful Naso and a couple of other smaller fish to it. Since the UVS did not work I decided to take all my fish out and put them in an emergency set up that was only 20g, while treating with Hypo the fish all got better and visible Ich was gone, but it was really cruel of me to put all those fish in a 20L, so I ended the treatment too soon and put the fish back in the DT. Within a few days, the fish were all covered with visible Ich. At this point I didnt now what else to do, and I didn't want to lose anymore fish, so I decided to dose Ich attack at above the recommended dosages. With in a few days, all visible ich was gone and within a week, all signs of ich infestation were gone! My fish started eating again, the heavy breathing went away, no scratching against the rocks etc. I have not since experienced anymore ich problems. I attributed the elimination of ich in my DT to this product. The most interesting thing about this anecdotal experience is that none of the corals were affected by the product. during the dosing period the hammers had full extension and the Xenia continued to spread all over. The majority of the corals I keep now are the same that I had when I treated with this product. Based on my experience, I conclude that this product was not only safe for "some" soft corals, but I also was able to eradicate Ich. I wonder if anybody has performed any experiments using this product. I would like to find out if this product actually works every time or if my case just happened to be a special one.