Browning of corals

[Marksfish]

Until accurate and cheap ways to measure doc become available, if anyone is concerned about the levels just use granular activated carbon in addition to your scrubber.

What sort of quantities of carbon are we looking at please? My green acro is very brown anf my purple plating monti is a copper colour. I'm sure it's not a light issue, so am looking towards carbon.

Mark

[chrisfraser05]

so a bag of carbon will do it?

[dtyharry]

It will certainly do no harm although as Santa said browning is usually caused by excess inorganic nutrients like nitrate and phosphate which carbon will not remove. All depends on whether you believe Santa who insists that you cannot have too much doc or whether you wish to maintain it at natural reef levels. Sps in particular have evolved in low nutrient, low doc waters.

[Marksfish]

But what size is a bag of carbon?

[chrisfraser05]

I'm very tempted to go back to skimming aswell as scrubbing but will decide after I boost the scrubber and let it settle a little.

[kerry]

I have never seen a use for carbon besides making my pocket book lighter or to remove meds in my FW tank decades ago. Have they come up with some new stuff???? Normally carbon only lasts a day or two max. What is in the carbon that traps or removes the DOC??? How does the carbon attach or grab DOC's and remove it from the water column??? SEE, ITS ALWAY THE DOC's THAT GET ME!!!

[Ace25]

This video better explains different carbons. http://www.youtube.com/watch?v=oVpRGzerJFI
And here is a good explanation on how it is made and how it works. http://www.wetwebmedia.com/ca/volume_7/ ... arbon.html

[SantaMonica]

but rather the coral absorbing the DOCs

Yes the coral animal itself eats DOC for growth. As your SaltAquarium quote says, it has nothing to do with zoox.

(The nutrients might increase the number of zooxanthellae in the coral, but it is possible that the nutrient overload increases the susceptibility of coral to diseases.)

Of course if ammonia is high, or even excess N and P, there would be a problem.

it is still a tiny fraction, think about it, one part organic carbon, 999999 parts water

Using your your own definition, 1ppm, it is the largest amount of carbon in the ocean (lakes too). If you don't think 1ppm is a lot, try 1ppm of phosphate, or 1ppm of ammonium. Why try to minimize the sound of it?

The carbon keeps levels of doc at reef levels

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?

Sps in particular have evolved in low nutrient, low doc waters.

What? Don't you remember anything of the studies that you said you read? The oceans, and especially reefs, have VERY HIGH doc levels.

[kotlec]

Very informative discusion by the way.

[Ace25]

Excess DOCs = more food for corals = more happy conditions for zoox to thrive and multiply... in extremes this leads to brown corals due to over saturation of zoox. What that point of "excess" is, is anyone's guess since we have no way to test for it at home, so we can only go on visual clues.. like my tank, first 5 months, corals went from brown to colorful because I took them out of another system with high DOCs into a new system with low DOCs. At month 5, corals started losing color again and browning out, at month 6, corals are now completely brown. I put in carbon last week and now the brown is very slowly going away and I am starting to see color in the coral again (colors other than brown). Pretty clear to me that excess DOCs is what is causing my issue with SPS corals. I do not have any browning problems with any other type of coral (LPS, softy, anemones.)

Not saying DOCs are bad, only excessive DOCs are bad in a closed system (aquarium). An ATS creates DOCs, not removes them. If you use an ATS only system for filtration, what method do you have in place to remove the DOCs from the system? If your relying on simply bacteria and corals to do that for you it is probably not going to be enough for almost all aquariums that have SPS corals in it. If you try to put in bio-pellets to eat the DOCs, you end up killing your ATS screen because the bio-pellets/bacteria will eat ALL the food out of the system much faster than the ATS can do it. The more the corals absorb DOCs, the more food the coral will create as a byproduct for zoox within the coral, making it a happy environment for zoox to multiply out of control in turn making SPS corals brown.

I love algae scrubbers, I think they are the best single type of filtration out there, but not without its shortcomings. DOCs being one of the shortcomings. Unfortunately for SPS keepers I do not see any way that an ATS can be used as the sole filtration method and no water changes. Either you need to add a secondary filtration type (carbon, skimmer, etc) or you need to keep up on weekly water changes in order to fill in the gap that the ATS has in terms of complete filtration. I am only talking about SPS coral tanks.. softy corals are much more forgiving and so are most LPS corals. As always, just my opinion.