Browning of corals

[Ace25]

Any sugestions why my acros still brown ?

How much carbon are you running? What type of carbon? And how often are you replacing it? On my 55G tank, the one that corals are going better in, things were good the first 5 months after setup, then at month 6 was when I think DOC levels got too high and some SPS corals browned out (They were brown in the 75G tank, moved them over to the 55G and they colored up for months, then started browning again in that tank). That was when I added carbon. I put in A LOT of carbon to reduce the DOCs initially. 3 cups of ROX 0.8 carbon replaced weekly for the first 3 weeks was what I did, 2 cups worth in a filter bag in the sump and 1 cup in a filter bag in the overflow... now I am using 2 cups of carbon in a bag in the overflow and replacing it every 2-3 weeks since my corals look like they are moving in a positive direction. Just going off observation, but I think the DOC levels are good now and why the corals are coloring up more each day. Similar thinking with carbon as people who are working on a Phosphate problem. If you have phosphates in the 1.0+ range and try and use GFO to fix the problem, it is going to take a ton of GFO initially to do that much work, a reactor full and replaced every 2 days for a month to get levels down to the .03-.09 area, but once you get levels down you can use a smaller amount and replace it far less frequently. Only difference is I can't measure DOCs like I can phosphates, I can pretty much only go off observations to give me clues on how things are going and guess on the correct amount of carbon and replacement schedule.

[kotlec]

Im using best carbon I could find. I will try to use more to make initial clearance. That's good idea.

BTW how many is cup ? Is it kind of american standard ?

[Aeros]

Im using best carbon I could find. I will try to use more to make initial clearance. That's good idea.

BTW how many is cup ? Is it kind of american standard ?

Invented by Stanley, It's a unit of measurement based off of a semi-annual award given to a group of players who hockey the hardest against other hockers.

[kotlec]

Then I have much to do. First buy skates, then learn to play hockey. Lastly I have to win cup. Only then I will be able to measure right amount of carbon for my tank :mrgreen:


Seriously google helped me : A metric approximation to the US cup measurement equal to a quarter of a liter.

[Doompie]

Finally found some research that kinda points this issue out:

From the book "Coral reefs an Ecosystem in transition" Part III "Light as a Source of Information and Energy in Zooxanthellate Corals" - chapter 8 - Energy and Nutrient Fluxes..

So Browning is an swing of Zooxanthellae, right?

Quotes from research:

1) "with the assumption that within a colony under normal conditions, the symbionts are maintained at their carrying capacity, and their multiplication is further controlled by shortage of nutrients needed to match the carbon influx and the translocation of most carbon skeletons to the animal host. That the true doubling potential of the Zooxanthellae is on the order of a few days to a week has been demonstrated when corals are provided with seawater replete with nitrogen and phosphorus (Falkowski et al. 1993) and in the fast repopulation of experimentally bleached colonies (Koren et al. 2008)."

2) "The nutrient-limited, high-light corals readily respond to host factor stimulation and excreted as much as 250% against seawater as 100%. Interestingly, no such response is seen in low-light corals (Fig. 16). We interpret these resullts to be due to the relatively useless carbon acquired under high light that under nitrogen and phosphorus limitation cannot be utilized by the zooxanthellae for cell doubling. In the shade, each carbon atom can be used with the corresponding nitrogen and phosphorus ratios for new cell building (Dubinsky and Berman-Frank 2001)."

Zooxanthellae have the ability to decrease the amount of carbon taken by photosythesis, simply by lowering the photosythesis capacity..and that is darkening themselfs..

So the conclusion is that OR you have too much light for that coral so it can aquire too much useless carbon, combined with too low nutrients, which stimulates the browning of the Zooxanthellae..Or too much nutrients vs. too less light...

Another conclusion that can be made regarding this research:
When you have a "booming" growth of zooxanthellae (which makes them also looks brownish) it's only a case of too much nutrients (N and P).

Some good light info...: http://www.fishchannel.com/saltwater-aq ... light.aspx

For those who are interested, some info regarding DOC's and bleeching here:
http://sites.google.com/site/coralreefs ... umentaries

[Ace25]

Fantastic post Doompie!

Another conclusion that can be made regarding this research:
When you have a "booming" growth of zooxanthellae (which makes them also looks brownish) it's only a case of too much nutrients (N and P).

I still think there is more to this statement. Sure, the end result is true, but what actually leads to "too much N/P"? I still think corals absorbing excess DOCs and secreting N/P in the process is also a major factor to browning. You can't get much closer to the source for food (N/P) than zoox living inside a coral that is secreting food to feed the zoox. Kind of like how Santa Monica explains nutrient buildup in tanks, the rocks get it before the scrubber and feed algae in the display, in this case the corals feed the zoox before the scrubber can remove it. Just how I am thinking today.. more research may make me change my mind though. I certainly don't want anyone thinking I have the answer to this question, I just have theories.

[Ace25]

I saw Santa Monica posting on other sites about "too little light" being a cause of browning when coupled with too much food in the water. I want to show this is not the case for me. I actually replicate the SUN at mid day with my LED light (~2000 PAR!). So SUPER high light (much higher than typical MH setups ever got, not even a 1000w MH will touch my LED light in PAR output) and high nutrients still = dead corals. Not bleaching dead, but browning out, no polyp extension, and slow death over the course of weeks/month, not a RTN type event.

http://www.youtube.com/watch?v=bElFSUmg5MY

I no longer use any T5s, this pic was taken the first day the LED light replaced my 400w MH (which got 850 PAR with a 10k bulb).

[Floyd R Turbo]

I can't say that I speak from direct experience here, but I do recall reading in multiple places that when the switch-over from MH to LED happens, people tend to tune their light output to mimic what they were getting from the MH lamps, and the light is actually much more intense and focused than it was before. IIRC this led to some coral death and bleaching events. One thing I have also read many times is that PAR meters are not very good at registering blue light correctly. The bottom line here is that I think it would be good to look at some information on these types of things as well.

I know from my conversations with hydroponics guy when designing my LED scrubber fixture, he did not have very much good to say about PAR meters in general, mainly that they are not very reliable or accurate unless you get a very expensive one that can pinpoint a specific spectrum rather than giving you overall PAR, because that really doesn't tell you that much apparently. Also the same guy was closely involved in the development and design of a reef LED fixture, and his comment was that royal blue trumps all for growth, everything else is pretty much just for aesthetics. I can't quite tell from your pic of your fixture, but it looks like you have some 425/435 blues (the purple ones) and some cool whites. These may not be contributing as much to coral growth as the RBs are and may factor into this issue.

But again, this is all just regurgitated information. I could be completely off base, so feel free to correct anything I may have misinterpreted.

[Ace25]

I hear you 100% on the "switching to LEDs" thing. I actually agree 100% with it as well. A person has to understand how light works, what spectrum does what, and how much of what spectrum your using. I have a very good understanding of how light/spectrum/PAR works. Once you understand all that, you can still make use of a PAR meter. I agree, they are certainly not the most accurate tool, but even at $500 it is still the cheapest "light tool" and still useful if you understand how to use it and understand the spectrum your testing. Luckily I have a spectrometer at my disposal at work and have tested many light bulbs and LEDs myself to get spectral graphs and know what I am putting over my tank.

The reason why you can't just switch MH to LED and keep the same intensity is quite simple, MH lights put out a lot of spectrum that falls outside of the photosynthetic peaks. So most of the bright light we see is for our eyes and to see the different colors in the tank, where as with LEDs, the standard 50/50 mix of Royal Blue and Cool white puts out A LOT more 455nm light than any MH ever could. It is also a dim looking spectrum to our eyes, so we put a ton of blue to balance out the whites. If it were cool blue instead of royal blue it probably wouldn't be as big of a problem since most of those fall outside the photosynthetic peaks, but they also do not make corals glow like royal blues and actually make the water look like Windex to some if you use too many. So it is a double edge sword, we love the look royal blues give out, but by adding so much we harm our corals. To top it off, Cool White leds also put out a lot of 455nm blue. So when you add a light that is a 50/50 mix and turn it up to the intensity that the MH appeared to be, we are actually throwing 2x the amount of light at it in the 455nm range, which is why corals react negatively very quickly when you do this, usually by bleaching or RTNing.

So, knowing that a MH spectrum and the LED spectrum are quite different you can adjust your PAR ranges accordingly. It takes some re-learning but it is still easily done. It took me a year of checking PAR levels at certain corals under MH lights to get a feel for PAR levels for different corals, and with LEDs, even trying to calculate and adjust accordingly, it still took some re-learning to figure out what the new PAR reading corals liked. My light can do 2000 PAR at the surface, I don't run it that high (yet). I started off erroring on the low side so when my SPS corals were at 500 PAR before, I set them at 200 PAR under LEDs. I have since been slowly raising the PAR levels over the course of a year (next week will be 1 year running LEDs for me) and I am now actually up to 600 PAR at the coral and still brown.

On my first fixture (the one pictured above) I added different LEDs to cover the entire spectrum, ie. 12x royal blue, 8x cool blue, 4x cyan, and 16x cool, 4x neutral, and 4x warm whites. I wanted to cover the entire spectrum and since 420nm LEDs were not out last year, I ran 420nm T5s with the LEDs to cover the low end of the spectrum. One of the things I have said since the day I started using LEDs for projects is we really need full spectrum colors, like a full spectrum blue that is 420nm-480nm. This way we get the blue look we like without throwing an insane amount of a specific spectrum like royal blues. On my other light I run a simple 50/50 mix after seeing all those extra LEDs in my first fixture really didn't add much other than control over the color of the tank, but I also planned for that by having 48 LEDs over a 30"x24" footprint where as my other tank I have 24 LEDs over a 48"x14" footprint. Less LEDs, bigger area to cover, but since it is royal blue and cool whites, I don't need much to make my corals happy with the light they are receiving. That is the tank my corals are coloring back up in by using carbon in the tank. The last brown SPS stick I took out was under 600 PAR, and brown as can be, within a week under 400 PAR it started to color up. To me 600 PAR in one tank is = to 400 PAR in the other because the PAR I am getting @ 600 includes a lot more spectrum that fall outside the photosynthetic peaks and are almost useless to the corals. So same light levels in my opinion, higher light levels than my MH light before, the only difference is I use a lot of carbon in one tank and that happens to be the tank the corals regain color in.

Santa Monica has a nice theory, and I am not going to say he is wrong, I certainly do not have enough data to say anything close, but I do have my personal experience and it is telling me I don't think adding more light to a SPS tank run with only a scrubber will solve the issue we are talking about in this thread. As easy as it is to say "throw more light at it", there is a very complex method to actually doing that.

[dtyharry]

The only thing you have to worry about with elevated levels of doc are massively increased microbial growth on the coral surface which literally starves the coral of oxygen. Of this there is now no doubt. The debate as to whether aquariums with scrubbers produce excess doc will not end until accurate measurements are taken, currently beyond the scope of hobbyists.
It is no more complicated than that.
If you want to ensure your doc levels remain at natural healthy reef levels use activated carbon and if you are worried about tangs and lateral line disease and such use purigen or similar to keep levels low.
We can all argue until we are blue in the face but if you think your scrubber is producing excess doc which has not been proven incidentally, either stop using a scrubber or use carbon etc.