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Thread: Browning of corals

  1. #21

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    Re: Browning of corals

    From all my reading..... and I've been doing alot since friday lol... I would tend to agree with you there!

    My sps seem fine if a little dull but its my Zoa's i've noticed browning mainly. going to look into this

  2. #22
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    Re: Browning of corals

    I love this!! Well most of the time LOL. This means more research now!! I cannot get past the DOC's, AS ALWAYS!!! THIS IS MY BIGGEST HURDLE. There has to be something to control the DOC's. There has to be some kind of limiting factor to keep them as low as they are. If a tank cannot control DOS's then what is the problem??? It has to be flawed in some kind of way. The ocean can handle the DOC's with no problem. How does the ocean control them?? The ocean controls them by means of of ingestion (so to speak) by something that feeds on them and uses them up. If corals turn brown then I would assume that tank does not do a good job of mimicking what the ocean does. What limits a tank from performing like the ocean???? I believe there has to be some kind of factor there.
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  3. #23

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    Re: Browning of corals

    In new2scrub's post 'film algae on glass again', i mention a study by advanced aquarist in september 2008 measuring doc levels in various aquaria with different husbandry practices. Despite santa saying that the aquarium with high doc, over 5ppm, was a hastily constructed experiment that had not been given chance to mature, i do not believe this was the case. Check the acknowledgments, the water samples were supplied by a reef society with the exception of the author's own tank.

    The tanks that utilised granular activated carbon all had levels of doc in line with healthy natural reefs, 1.1pmm +-0.4. Tanks with skimmers had higher levels than this if they did not use carbon as well, showing how ineffective skimmers really are. The only tank with elevated levels above 5ppm was the tank with no skimmer and no carbon filtration.

    Quote Originally Posted by SantaMonica
    Bacteria and microbes keep levels of doc at (really, below) reef levels. Why are you adding vodka/pellets/zeo with one hand (in order to grow bacteria) and removing it with the other hand? DOC the the LIMITING factor in tanks. That means it is in SHORT SUPPLY compared to everything thing else needed to grow bacteria. That is why CARBON DOSING (ie. DOC dosing) works. Yes, dosing carbon is the same as dosing DOC, because vodka/pellets/zeo ARE doc. Don't you see how backwards you are making it sound?
    There are many drawbacks to the carbon dosing route such as overdosing, bacterial blooms causing oxygen starvation and the lack of any scientific evidence as to how much and when etc. Also to run these systems it is essential to have a very oversized protein skimmer to remove the bacteria which is produced. You only need carbon dosing if your goal is to grow these extra bacteria which in a scrubber system is not necessary because the phosphate and nitrate are absorbed by the algae.

    If you went the carbon dosing route without a skimmer the EXCESS organic carbon which you have dosed would increase bacterial levels to such a degree that you would probably kill all your fish and corals due to oxygen starvation. No, the bullet in your hand that is organic carbon did not kill you, but when it is fired through the gun that is increased microbial and bacterial growth, yes you will die. Good night!

  4. #24
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    Re: Browning of corals

    Harry,

    Can we have guidelines to GAC usage? How much, how often, what type and so on ? I thing trying this wont hurt at all. My corals are brown, but grow like mad (except one kind of zoa) and my scrubber is 5 x too big as per new feeding guidelines.

  5. #25

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    Re: Browning of corals

    A very interesting article on carbon and it's effect on DOCs.

    Mark

  6. #26

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    Re: Browning of corals

    February 2008 Advanced Aquarist did tests to see how long it took carbon to be saturated with DOCs and need changing. They took two different scenarios, one a skimmer set up with doc levels approximately 1ppm and an unskimmed tank at approx 7ppm. Taking a 100 gallon tank as an example it took approximately 40 days and 4 days for the low doc and high doc tanks carbon to become saturated respectively. That was using 100g of carbon.

    If you think you have high doc then it might be worth changing the carbon maybe once a week to start and once everything has settled maybe once a month.
    In the uk this would cost approximately 1 per month, very good value for peace of mind.

    Fig 12 in that article shows a graph for different tank sizes and carbon amounts and the saturation times.

  7. #27
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    Re: Browning of corals

    I haven't mentioned this yet, but one BIG concern with using carbon is it is now scientifically proven to be one of the leading causes of HLLE, so if you have tangs and other fish susceptible to HLLE I would advise people NOT to use carbon in the system. I would use Purigen instead.

    http://www.advancedaquarist.com/blog/ac ... le-disease

    http://www.advancedaquarist.com/blog/ac ... ne-erosion

  8. #28

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    Re: Browning of corals

    Quote Originally Posted by Ace25
    I haven't mentioned this yet, but one BIG concern with using carbon is it is now scientifically proven to be one of the leading causes of HLLE, so if you have tangs and other fish susceptible to HLLE I would advise people NOT to use carbon in the system. I would use Purigen instead.
    Yes if that was a concern purigen seems like it would be a great alternative. Here in the uk a 1litre pack costs 50. 100ml treats a 100 gallon tank for up to one month at a time and can be recharged up to 10 times. Even if you only recharged it 5 times to be sure that is 50 months of treatment removing organics which is cheap i tink you would agree compared to a skimmer! Bet in the US it is cheaper as well.

    Easy to tell when it needs recharging as it turns from white to brown/black. Anyone on here use it?

  9. #29

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    Re: Browning of corals

    I'm interested!!!!!

    So purigen does the job of carbon then???

  10. #30

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    Re: Browning of corals

    Very interesting discussion!

    Here's my 2 cents:

    I did some reading on DOC's and what they are, and what the effect is on corals. But there are only a few thing men can say about it..allot more is just unknown..

    So here are a few of my findings..

    Research on DOCS's on the Great barrier reef..

    This research writes in short that an increased ammount of DOC leads to coral bleech followed by mortality...but it differes between species, so to generalise SPS is to rough..also the levels are way out of tank levels.

    Standing stock of DOC is determined by a combination of carbon fixation via photosynthesis, consumption via heterotrophic bacterial growth, and import/export from exogenous sources.
    In general the standing stock is 70-80 uM..

    But they also state there is a huge differene between:
    1) Labile DOC - is rapidly turned over within minutes to days, and represent a major dynamical component of the marine carbon cycle
    2) Refractory DOC - can exist for thousands of years, maybe even milions and is Most of the measured standings..

    DOC measurements on coral reeds however show significantly other number: 34 to 160 uM, suggesting there is variable production and use of DOC on each individual reef. DOC flux is higher above the corals reef structure than surrounding waters. DOC levels are highest above coral reefs, and get lower closer to the structure.

    Measurements (eventhough where very hard) have pointed out that labile DOC is approximate 20% in some coral reef waters.

    Other interesting facts according this research:
    - Microbes consume most of the labile DOC and are carbon limited
    - On coral reefs complex interactions between DOC, microbial growth and filter feeders exists

    So the mortality problem is not the DOC is self, it is the uncontrolled microbial growth..(they outcompete the coralmicrobes)


    Antoher research

    The abstract of that research:
    "Here we experimentally show that routinely measured components of water quality (nitrate, phosphate, ammonia) do not cause substantial coral mortality. In contrast, dissolved organic carbon (DOC), which is rarely measured on reefs, does. Elevated DOC levels also accelerate the growth rate of microbes living in the corals' surface mucopolysaccharide layer by an order of magnitude, suggesting that mortality occurs due to a disruption of the balance between the coral and its associated microbiota"

    Also there has been multiple researches on release of DOC from (SPS)corals, they do release DOC's. Most of it is labile but netto they don't though.

    But one of the most interesting things i've read was this research

    Abstract:
    "Particulate organic carbon (POC) release was highest for corals (8.2 4.2 mg m2 h1), followed by benthic algae (3.9 0.7 mg m2 h1) and seagrasses (3.1 2.0 mg m2 h1). Dissolved organic carbon (DOC) release rates were highest for seagrasses (15.8 6.0 mg m2 h1), followed by algae (1.9 2.0 mg m2 h1), whereas corals displayed net DOC uptake. Benthic algae-derived organic matter stimulated planktonic microbial O2 consumption significantly more than seagrass- or coral-derived organic matter. In situ O2 loggers revealed significantly lower average O2 concentrations, particularly during the night, at algae-dominated sites compared to other benthic lagoon environments. This indicates effects of algae-derived organic matter on in situ O2 availability. We therefore suggest that shifts in benthic primary producer dominance affect ecosystem functioning owing to differences in quantity, composition and microbial degradability of the released organic matter."


    Also there is this reseachstill ongoing untill 2012..
    They try to find the Coupling between dissolved organic matter, algae, and microbes on coral reef platforms..

    "The observation of low DOC measurements on degraded reefs is decoupled from the high abundance of macroalgae, which one might expect would raise levels of DOC through the release of photosynthate into the water column. To explain this apparent paradox we propose that reef degradation, and the associated phase-shifts from coral to algal dominance, leads to elevated levels of algal exudates in the water column, which allows the microbial community to utilize the standing stock of semi-labile DOC"


    Research ends with:
    "To futher understand the relationship between microbes, DOC,and coral reef decline there are many research questions to be answered.."

    One conclusion we can make though: Fleshy algae release primarly/only Labile DOC..

    I realy would like to suggest to everyone to have a look at this book:
    http://books.google.nl/books?id=4hI5XCc ... al&f=false

    From page 241 it's all about the importance of algae..

    *tip: search for the e-book version of "Coral Reefs: An Ecosystem in Transition"

    Regarding the browning of the SPS:

    There are so much more factors that come into play, here's an interesting article with a different perspective :
    http://reefkeeping.com/issues/2007-01/atj/index.php


    Final research which is worth reading: (2001)
    http://www.rsmas.miami.edu/groups/bioge ... ansell.pdf

    I think the conclusion says it all:
    "We have more to learn about what limits the amount of DOC in the ocean, what controls its production and lifetime, and what DOC is composed of"

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