I am so P off

[Dive_Master]

About 3 months ago, I replaced my PC lights with MH 250W in a 20 inch deep tank.

I hate what happend to my tank. I had a very slow acclimation period, but my tank is falling apart.

My brain corals are either bleaching or dying. All my LPS corals are showing signs of stress. The SPS had and have very slow RTN. Only one is doing OK.

I have been moving these lights up to 15 inches (started at 10 inches) above water level. I have put glass tops back on, and nothing is working.


This tank was beuatiful under PC lights and now it looks like crap.

I think I made a big mistake. I am so frustrated I do not know what to do.


Does anyone know what I should do next.


Everyhitng was growing and looking great 3 months ago.

I am lost for solutions outside of going back to PC ligths.

[Ninong]

I hate what happend to my tank. I had a very slow acclimation period, but my tank is falling apart.

That's a fairly substantial difference in light intensity. In nature it takes a minimum of three weeks for corals to complete the physiological changes necessary to adapt to changing light conditions, either up or down. They have to either produce more zooxanthellae in the case of reduced light intensity or expel zooxanthellae in the case of increased light intensity. Otherwise you end up with oxygen poisoning if you have more zooxanthellae than required for the new higher light conditions. They also have to modify the size of the PSU's in the zooxanthellae either up or down.

The best way to handle such changes is to figure out a way to make the difference between the old intensity and the new intensity as little as possible and gradually increase it over a period of several days to several weeks depending on the difference between the old lighting and the new. I really don't know what to tell you now other than maybe trying to reduce your present light intensity back to something close to what it was originally and then wait for things to improve before trying to build it back up.

[Samper]

Would it be a possibility to just run the halides for an hour or so the first day and increase by 15 minutes every day until he's up to a full day?

[scubadude]

I feel your pain bro, been there done that Definately salvage what you can, and start over again. Just dont let the death of your corals be in vain. You do have some options though still .

Use shadecloth between lights and water line....you can use multiple layers of thin shadecloth and gradually remove them, thus you arent fondling the corals and and you are still light acclimating them.

I Like samper's idea too, I believe Eric B. has some info on flashing MH's for better acclimation. What exactly is your photoperiod of your MH's? If your running like 6 hrs say constant you could try running for 8 hrs but your lights are only on for 30 min. of every hour (but this time frame you manually increase a little at a time). I believe this method is MUCH healther for photo adaption. A good timer could automate this too.

[Ninong]

Would it be a possibility to just run the halides for an hour or so the first day and increase by 15 minutes every day until he's up to a full day?

The answer to that question is more complicated than you might expect. Yes, the total quantity of irradiance that is received in a day makes a difference. That's why people with less than very strong lighting will often run their lights 13 or 14 hours per day instead of the usual total of 12 hours per day. For example, if you have one tank with two 250w metal halide lamps and another tank with two 400w metal halide lamps you might run the 250w lamps 12 hours per day vs. 10 hours per day for the 400w lamps to close the gap between the two tanks in total irradiance per day. That works as far as increasing the total quantity of PAR that the corals receive in a day but his situation is not the same.

Corals, or more precisely, their zooxanthellae, have to adjust to not only the total quantity of light that they receive daily but they also have to adapt to the variation in intensity of the light that they receive during a single day. That's why very shallow water SPS species undergo photoinhibition during the middle of the day during low tide. The zooxanthellae actually reconfigure themselves on a daily cycle to adapt to changing light intensity. They do that in a few different ways.

In nature changes in light intensity are not all that sudden. They happen gradually, allowing the corals time to adjust. That's not what you would have in an aquarium when you turn on brand new 250w metal halide lamps that are perhaps three times as intense as your previous lighting. Yes, reducing the total photoperiod is one way to reduce the total amount of irradiance but that doesn't help you with the fact that you are still asking the corals to adjust to an extreme difference in intensity. This is not easy to explain. ;; Let's try an example. If you are switching out your existing 250w metal halide lamps that have been running for the past 12 months and installing new lamps that are the same as the old ones, only new, then you could get away with lowering your photoperiod from say 12 hours/day to 9 or 10 hours/day for a week or two to allow the corals time to adapt to the difference. Ideally you would want to simply raise your light fixture higher above the tank so that the intensity of light incident on the corals is about the same and then you would gradually lower it. Or you could achieve the same effect using some sort of shade cloth over the tank and then gradually removing layers of it, assuming there were two or three layers.

But... Trying to go from say "x" intensity of light to "xxx" intensity of light is an entirely different matter. Simply reducing your photoperiod from 12 hours/day down to 4 hours/day won't work. Yes, it would give you about the same total amount of irradiance daily but the corals would still have to deal with a much more extreme diurnal variation than they experienced before.

It's really hard to explain something like this in a couple of paragraphs because it takes up entire chapters in books and I don't feel like getting into the physiology of PSU's and diurnal and seasonal variations in the structure of individual cells.

The bottom line is that you can only go so far in reducing your total daily photoperiod. It helps in certain situations but it won't cut the mustard all by itself in extreme situations. However you achieve it, your goal is to make the difference in intensity AND the difference in total daily irradiance as gradual as possible. The greater the difference between the old and the new setup, the longer the period of adjustment.

[Dive_Master]

Everyone,

I had no idea this was going to be that complicated. I thought I had broken the lights in a very long time. 1 month or so., but I guess I was wrong

Now my corraline is bleaching where it was great looking pink for a long time.

Thank you everyone for your feedback!

[Poseidon]

If your coralline is bleaching that is an indication of low Ca and Alk levels, as coralline will grow in low light areas. Have you tested those lately?

[Samper]

Ninong I understand what you're saying about the corals zooxanthellae having to adjust to the lighting changes and having a hard time with sudden changes. Is there any research showing that corals in captivity have sped up this process adjusting to our lighting? Cause we flip a switch and have light, yes we have actinics and so on but no matter how you set up your lighting it can never be as gradual of a change as a natural photoperiod.

[Ninong]

Ninong I understand what you're saying about the corals zooxanthellae having to adjust to the lighting changes and having a hard time with sudden changes. Is there any research showing that corals in captivity have sped up this process adjusting to our lighting? Cause we flip a switch and have light, yes we have actinics and so on but no matter how you set up your lighting it can never be as gradual of a change as a natural photoperiod.

That's not the sort of change in light intensity that I am talking about, although it is better to not have a completely abrupt change from total darkness to a fully lit aquarium for the benefit of the fish. Many fish spook easily and jump from the tank when there is an abrupt and total change in the light intensity. This doesn't really have any effect on the corals at all. Not that it matters much, but if you are using metal halide lamps, they take at least five to ten minutes to achieve full intensity anyway.

I wasn't very clear in my explanation at all but I hate to have to rewrite the whole mess. Let's forget about diurnal variations for the time being. I was just throwing that in to point out that corals in the wild do make changes in response to both seasonal variations and diurnal variations. They vary the population densities of their zooxanthellae and even modify the size of the chloroplasts to better suit their environment. The same species is often found over a range of as much as 20 meters or more. To adapt to the variation of light intensity over that depth range, they not only change their zooxanthellae, they even change their morphology (shape). (They change their shape in response to the intensity of the water flow, too, but that's not what we're talking about here.)

As to your question about the length of time required for corals to adapt to changes in intensity, I don't believe it can be "speeded up." Here I am talking only about the changes necessary for corals in an aquarium to adapt to three things: Total quantity of irradiance over a given daily photoperiod, light intensity and changes in the spectral distribution. If these three things are not all that different from the previous lighting, then there won't be as much work required on the part of the corals. If the changes are significant, then they will have more work cut out for themselves. And I haven't even mentioned the changes necessary to adapt to changing spectral distribution. Different pigments utilize different parts of the spectrum. If you switch from 20,000K lamps to 6500K lamps or vice versa, you are asking your corals to not only change their zooxanthellae, but also to make radical changes to their pigments and auxilliary pigments. This is why I wish I hadn't answered the original question. There is just no way to adequately respond to this question without going into pages and pages of explanations.

Let's just say that if you are making ANY sort of drastic changes to your lighting, you should do so gradually -- especially if you are INCREASING things. If you are going from 175w 10,000K metal halides to 400w 6500K metal halides, you have your work cut out for you. It can be done without any ill effects, but it will take time and careful attention to procedures.

[Samper]

As to your question about the length of time required for corals to adapt to changes in intensity, I don't believe it can be "speeded up." Here I am talking only about the changes necessary for corals in an aquarium to adapt to three things: Total quantity of irradiance over a given daily photoperiod, light intensity and changes in the spectral distribution. If these three things are not all that different from the previous lighting, then there won't be as much work required on the part of the corals. If the changes are significant, then they will have more work cut out for themselves. And I haven't even mentioned the changes necessary to adapt to changing spectral distribution. Different pigments utilize different parts of the spectrum. If you switch from 20,000K lamps to 6500K lamps or vice versa, you are asking your corals to not only change their zooxanthellae, but also to make radical changes to their pigments and auxilliary pigments. This is why I wish I hadn't answered the original question. There is just no way to adequately respond to this question without going into pages and pages of explanations.

I'm quite curious about this......

Can you point me to a few links or books for further reading?
oh btw have you read this
Marine Chemical Ecology by McClintock and Baker

I just ordered it a few days ago and I'm hoping you or someone here has read it in case I get stumped.

[Ninong]

I'm quite curious about this......

Can you point me to a few links or books for further reading?

Sure.

Coral Reef Ecology by Yuri Sorokin: http://www.amazon.com/exec/obidos/se...622015-8236933 Hardcover is out of print and the paperback version is almost impossible to find. I finally found the paperback version at a college bookstore and paid the full $89.95 plus shipping. I can't remember which store. It might still be available online at U.K. booksellers, but only in paperback. I even saw it discounted there but that was after I had already ordered mine.

The Ecology of the Indonesian Seas, both volumes: http://www.walmart.com/catalog/searc...&Continue.y=13

oh btw have you read this
Marine Chemical Ecology by McClintock and Baker

No.

P.S. -- In addition to the references I gave above, I have most of the typical "hobby" literature. So sometimes it's hard for me to say exactly where something came from.

[Samper]

Thanks again Ninong