Hi temp spike....bleaching, thoughts?

[PerryinCA]

Well about half of those I can throw out and not read as they pertain to species that I don't have, or look to me to simply be part of "list" of references made to overwhelm possible readers.

If Sorokin's info is valid, then Ron is preaching to keep our reefs at the "upper limits". Wouldn't the median be most ideal? I would think so. For one, not all coral come from that high of temp, 2 why flirt with disaster by keeping tanks at the upper limits?

I think my experience as well as Randy's prove that those "small" and "worry-less" 4-5 degree temp spikes that reach into the upper 80's can and do often result in negated coral health.

What exactly is considered a "long-term" exposure to Sorokin? Day, week, month?

Here's a couple that prove some interesting reading:

Title : The Biology of heat shock proteins and molecular
chaperones / edited by Richard I. Morimoto,
Alfred Tissiáeres, Costa Georgooulos.
Publisher : Plainview , N.Y. : Cold Spring Harbor Laboratory
Press, 1994.
Description : vii, 610 p. : ill. ; 24 cm.
Series : Cold Spring Harbor monograph series ; 26.

Anthony S L, Lang J C and Maguire Jr. B
1006
Causes of stony coral mortality on a central Bahamian reef: 1991-1995
Proc 8th Int Coral Reef Symp, Panama
1789-1794


Here's an interesting excerpt from:

Brown,-B.E.; Suharsono. Damage and recovery of coral reefs
affected by El Nino related seawater warming in the
Thousand Islands, Indonesia. CORAL-REEFS. 1990. vol. 8,
no. 4, pp. 163-170.

Extensive coral bleaching occurred during seawater warming
(as a result of the 1982/3 El Nino Southern Oscillation
event) in 1983 on the shallow reefs in the Java Sea. Mean
seawater temperatures rose by 2-3 degree C over a six month
period with values greater than 33 degree C being recorded
between 1200-1500 h. As many as 80-90% of corals died on the
reef flats at the study sites, with the major casualties
being branching species in the genera Acropora and
Pocillopora . Five years after the event the community
structure of the study sites has recovered significantly,
though coral cover is still 50% of its former level.
Contrasting patterns of recovery at two selected sites, in
close proximity to each other, are discussed.

This reference:

Cortes,-J.; Murillo,-M.M.; Guzman,-H.M.; Acuna,-J. Loss of
zooxanthellae and death of corals and other reef
organisms on the Caribbean and Pacific coasts of Costa
Rica (SPA). REV.-BIOL.-TROP. 1984. vol. 32, no. 2, pp.
227-231.


sites that temperatures of 33-35 caused mass bleachings and coral death.

Another:

Eakin,-C.M. The 1982-1983 El Nino: Impact of eastern Pacific
reef carbonate budgets and implications for severe
bleaching disturbances. PAC.-SCI. 1992. vol. 46, no. 3,
p. 377.

*note* from 86 degree el nino temps.

Yet another:

Gates,-R.D. Seawater temperature and sublethal coral
bleaching in Jamaica. CORAL-REEFS. 1990. vol. 8, no. 4,
pp. 193-197.

more:Glynn,-P.W. Coral reef bleaching in the 1980s and possible
connections with global warming. TRENDS-ECOL.-EVOL.
1991. vol. 6, no. 6, pp. 175-179.

more:
Glynn,-P.W. Coral reef bleaching: Ecological perspectives.
CORAL-REEFS. 1993. vol. 12, no. 1, pp. 1-17.

Jokiel,-P.L.; Coles,-S.L. Response of Hawaiian and other
Indo-Pacific reef corals to elevated temperature.
CORAL-REEFS. 1990. vol. 8, no. 4, pp. 155-162.

Here I quote fromt the abstract: "Bleaching can be
induced by short-term exposure (i.e. 1-2 days) at temperature elevations of 2 degree C to 4 degree C above normal summer ambient or by long term exposure (i.e. several weeks) at elevations of 1 degree C to 2 degree C. Corals in both tropical and subtropical locations live at temperatures close to their lethal limits during the summer months. Temperature elevations above summer ambient, but still below the bleaching threshold, can impair growth and reproduction."

Porter,-J.W.; Fitt,-W.K.; Spero,-H.J.; Rogers,-C.S.; White,-
M.W. Bleaching in reef corals: Physiological and stable
isotopic responses. PROC.-NATL.-ACAD.-SCI.-USA. 1989.
vol. 86, no. 23, pp. 9342-9346

Warner,-M.; Fitt,-W.K. Mechanisms of bleaching of
zooxanthellate symbioses. AM.-ZOOL. 1991 vol. 31, no.
5, p. 28A.

Of all those (which are but a few of the ones I have been reading recently) none got my attention more than "Temperature elevations above summer ambient, but still below the bleaching threshold, can impair growth and reproduction."

Even pre-bleaching temps can cause growth impairment. Thats a pretty large implication.

I am still reading, and will use some of the references you posted to hemp my understanding.....

[This message has been edited by PerryinCA (edited 05-27-2001).]

[Ironreef]

fwiw my tank is 87 been there for a few days. i don't like it this high but its not affecting my corals. I use to always worry about keeping it under 80. but now i don't. 87 is kinda high so now i just keep a fan on it all day. had to buy a new one for the sump should go down. If you read some of those refferances theres more than global warming theres dust and pollution that contribute. Heat may not good but usually theres a chain of thing that can affect the corals. One thing is how much did the added halide add to the heat? i would be more concered about that adding heat if I had a heat problem? Thats whats stopping me heat and eletric bill. I would like to add 1 400w. But IMO it doesn't matter who says what I listen to my corals ,there was a time not to go above 80. it created a lot of stress.4 me, Ron S says its okay seemed like a relief but I let my corals tell me. But at least i don't stress on 82 anymore.Theres alot of things ppl say that never worked for me, few very things I accually liked or could get right.



[This message has been edited by Ironreef (edited 05-27-2001).]

[PerryinCA]

Hey Iron,

So far (only been a day) heat hasn't risin above 81.9 with the extra MH, but it was only on for a few hours (but my god what a difference!)

I totally agree with you on the heat issue, and its a good thing you don't follow Dr. Ron "blindly" as some people seem to. I really get the feeling sometimes people take what he says without question simply because he is "accessable". Personally I never worried about temp. until this episode. Last summer I had temps in the higher 80's, but the tank wan't nearly as populated so I guess the stuff in there wasn't effected.

The increase in lighting likely won't help the bleached corals....but they got moved down and should bounce back. From what I have read, the bleaching episodes in the wild typically take a year for 70% of the ZA to be in population again. Whats odd, is that those 70% are far more efficient than the original populations....I'll have to look into that more.

As for the global warming...I wasn't really using those references in that respect...but info about effects on coral during times of abnormally (unusual) "high" temp episodes seemed relevent. The last 4 el nino's have brought respectively higher temperature peaks in the reefs, and the coral bleaching episodes are getting worse. Correlation? I think so. I am sure that the extra 7 years of pollution don't help, but I'll bet a dollar to five that its mostly caused by the abnormally high temp spikes.


-Perry

[Ninong]

Perry, the first reference is to a study of how normal behavior and metabolism are related to temperature, and what happens at the lower and upper limits of the range. The second reference is to conditions on coral reefs. I believe the other references are all studies of physical conditions in situ.

The reason you had massive bleaching during the 1983 El Niño was because it was the most extreme of the 20th century. Also, one of the things that I didn't see in the excerpt you posted was the fact that most of the damage in the tropical western Pacific was caused by prolonged exposure at low tides. This was exacerbated by the fact that sea level during the El Niño event dropped by 50-70cm in the western Pacific. (Temps in the western Pacific rose by 2-3C, and in the eastern Pacific by 4-6C.)

The fact of the matter is that there are no bleaching events of note prior to 1960. Just more evidence of global warming.

Corals can endure a temperature of 87F for extended periods (in the wild). The stress starts when the temperature is above 89F for extended periods (in the wild). Many corals endure diurnal temperature spikes higher than that for a few hours per day (in the wild). Acropora can even endure total exposure for several hours twice a month at low tides.

I don't think you will get anywhere arguing that 81-84F is unnatural or unhealthy for reef animals, certainly not in the wild anyway. You might want to direct your research into whether these temperatures, although perfectly safe in the wild, are risky in our little glass boxes.

All of Dr. Ron's arguments are based on duplicating natural conditions. The counter argument would have to be based on why this may not be a safe way to set up a home aquarium, not on whether his temperature and salinity recommendations are unnatural.

Ninong [img]/ubb/smile.gif[/img]


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"It's very important for folks to understand that when there's more trade, there's more commerce."— George W. Bush, Quebec City, Canada, April 21, 2001

[Ninong]

Originally posted by PerryinCA:

If Sorokin's info is valid, then Ron is preaching to keep our reefs at the "upper limits". Wouldn't the median be most ideal? I would think so.

Perry, what exactly is the temperature that Ron recommends? I believe it is 82-84 degrees Fahrenheit.

He mentions in his article on temps and salinity that 84F is a more natural temperature for animals from the central Indo-Pacific. I believe his current recommendation on his Reef Central forum is 82-84F. I have not seen him recommend anything higher than 84F in the past two years, although Delbeek said that he thought Dr. Ron used to advocate temps as high as 86F.

Here is a brief excerpt from Ron's article:

"Animals maintained near their physiological optimum will need to be fed regularly and adequately for growth. As an example, I maintained a small Heliofungia for an 11-month period during which time it almost tripled in diameter. It was fed the equivalent of one to two feeder goldfish per day. It eventually succumbed to damage from a predator inadvertently placed in my tank, but was growing and thriving prior to that time.

At normal (for the organism, not the aquarist) temperatures and light conditions, to assume that corals and other animals can get full nutrition from their endosymbionts is to ensure that they will not survive (Sorokin 1990a, b and 1991). They will need to be fed or the light intensity increased well beyond the normal range for the organisms. Unfortunately, few of these animals are generalist feeders, and their survival will depend upon finding an adequate and appropriate diet. Other reef inhabitants will need to be fed more frequently as well. This provides a continuing challenge, but the variety of foods on the market today generally makes finding an acceptable food not too difficult."

Incidentally, Ron uses a lot of the same statistics that Sorokin uses. Sorokin has a very detailed sediment infaunal population study that happens to be exactly the same as the figures Ron always cites.

You seem to be under the impression that Ron is recommending temperatures at the upper limits of normal ranges--not so. You are correct that temperature increases of as little as 1-2C above the normal upper limit can be deleterious. But if you check out the second reference, you will find that the average temperature of the 1,000 coral reefs studied was 81F. Many reefs had annual averages higher than that, even as high as 85F for the annual average at a few reefs. Some reefs had annual averages as low as 70F. But the average of ALL of those reefs was 81F.

A recommendation of 82-84F is not at all extreme in comparison to natural conditions. Is it safe for a reef tank??? That's a different question. You might want to shoot for 81-82F for your tank. This has always been the target range that I thought might offer the benefits of avoiding harming the animals by maintaining them at their lower limits like 75-77F might, while at the same time allowing a bit more safety on the upside. The counter argument is that an animal adapted to 84F can better tolerate a rise to 88F than one adapted to 81F. But if you aim for 81-82F, maybe your mishaps won't be higher than 85F or so.

Ninong [img]/ubb/biggrin.gif[/img]

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"It's very important for folks to understand that when there's more trade, there's more commerce."— George W. Bush, Quebec City, Canada, April 21, 2001

[PerryinCA]

I am not trying to argue with the corals ability to withstand those temps, or live in them (although I don't agree with some...more on that later). Once again, I am trying to stay away from anything concerning global warming, and am concentrating on the temp recommendations for tanks as they pertain to certain corals.

I don't think you will get anywhere arguing that 81-84F is unnatural or unhealthy for reef animals, certainly not in the wild anyway

Not in some cases... but as a general statement this ranks right up there with Watts per gallon. A month ago where I was diving in hawaii and surface temperatures were 74-76, and are right now at about 77.5 degrees. I have a hard time believing that those animals would be perfectly healthy if there were to be a rise up to 84. I think its a matter of geography. There are some areas that are commonly in the 82-85 range, but not all of them, so I don't think a blanket statement like that is applicable when our coral come from various different locations. For instance, Samoa is presently 78 degrees.

My argument has never strayed from the tank. I never intended to get into an debate over "natural reef temps", or whether a natural temp of 81-84 was healthy or not. I was simply using the elevated temps/bleachings as a reference, which support my current thoughts which are that I feel a tank temp of 79-81 is safer, and more appropriate than one of 81-83 (or higher).

The 1983 was the milder of the 3 most recent widespread bleachings from everything I have read. The last one caused 80% lossess in many areas, and according to the references I posted, the bleachings were not caused by low tide exposure, but mostly by temp increases and irradiance levels (maybe thats what you meant?).

Corals can endure a temperature of 87F for extended periods. The stress starts when the temperature is above 89F for extended periods

This I will totally disagree with. I have already proven different. One day at a recorded max of 87.3 was all it took for some of my acros to bleach. Some may be able to possibly even most, but definitly not all.

Ron's recommendations are based on the fact that there is more biodiversity in the area's with those temps, so it must be better for reef life. That may be true, but not all coral we get come from these environments. And, saying that "this is more diverse, so this is a better temperature for our reef" just doesn't seem logical.

Beyond the high temp effects on O2 saturation can cause available oxygen be detrimentally low in systems.

Taken from an abstract Sanjay posted by:William K. Fitt1, , Barbara E. Brown3, Mark E. Warner1, 2 and Richard P. Dunne3

(1) Institute of Ecology, University of Georgia, Athens, Georgia 30602, USA
(2) Department of Botany, University of Georgia, Athens, Georgia 30602, USA
(3) Department of Marine Sciences and Coastal Management, University of Newcastle upon Tyne, NE1 7RU, UK

'It should be clear that the upper temperature limit for life cannot be accurately defined' (Schmidt-Nielsen 1996'

And I totally agree with that. Fact is we don't know what the temps are "too high".

Another quote from the same article "Many (if not most) corals have already lost half or more of their complement of symbionts by the time a human is capable of detecting lighter coral color, even in so-called 'non-bleaching years' (i.e. seasonality). In other words, all corals appear to experience the physiological stress of reduced tissue biomass and concomitant loss of algal symbionts weeks to months before the human eye detects any signal."

So even when we have these tank temp "spikes" and the coral seem fine, they might have lost a fair amount of symbionts do to un-visible bleaching.

There are just too many reasons that I would rather keep my tank at a "cool" 80 as opposed to what Ron recommends. There are surely somethings I would listen to noone else one, but coral physiology is far from Ron's specialty.

-Perry

As a post script...I replied to your first post, and after reading the second, I feel we are pretty much in agreement. Last I had seen Ron advocated temps 83-85, I guess thats changed, or perhaps my memory eludes me. Anyhow, reef on!

[This message has been edited by PerryinCA (edited 05-28-2001).]

[Ninong]

Perry, when I said "Corals can endure a temperature of 87F for extended periods. The stress starts when the temperature is above 89F for extended periods.", I was talking about the wild, I wasn't talking about anybody's reef tank.

Hawaii is at the extreme outer limit as far as coral reefs are concerned. It's one of the areas that lowers the average down to 81F. It is not at all typical of reefs in the central Indo-Pacific. We do get a few fish from Hawaii but no corals. Most of the corals come from Indonesia, the Philippines, Fiji and other areas of the tropical Indo-Pacific where temperatures are much higher than in Hawaii.

Looks like it's in the 80's in Fiji right now. Looks like it's above 79F most of the year there.



You said: "Ron's recommendations are based on the fact that there is more biodiversity in the area's with those temps, so it must be better for reef life. That may be true, but not all coral we get come from these environments. And, saying that "this is more diverse, so this is a better temperature for our reef" just doesn't seem logical."

His recommendations are based on finding the the area of maximum diversity for a particular genera and saying that the temperatures in that area are ideal for that genera. So if you are keeping corals that are not typical of the central Indo-Pacific region, you would need to determine the temperatures at the center of their distribution. But he is saying much more than that, he is saying that temperatures at the lower limits, or upper limits, of an animal's tolerance have long-term deleterious effects on the health of the animal. All of these studies have already been done and all of the figures are published. Respiration rates and growth rates have been measured at different temperatures, etc. It's not a matter of guesswork. The only argument is whether or not it is relevant to reef tanks.

Incidentally, in his article he points out that his recommendation is based on animals from the central Indo-Pacific. If someone is keeping animals from other regions they should consider the temperature differences, if any.

Ninong [img]/ubb/smile.gif[/img]






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"Neither in French nor in English nor in Mexican."—George W. Bush, Declining to answer reporters' questions at the Summit of the Americas, Quebec City, Canada, April 21, 2001

[Ninong]

Here is someone who maintains SPS tanks at the same temperatures as recommended by Ron:

"Temps from 80 to 86 F which might seem high to some are more normal for these corals. My tanks run at those temps. The benefits from running lower temps 74-78 F are that disease outbreaks (RTN) occur less often but the drawback is that growth is slowed." -- Steve Tyree [11/1/98]

Of course you could argue that he is more interested in growth since he sells SPS frags.

Ninong [img]/ubb/biggrin.gif[/img]


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"Neither in French nor in English nor in Mexican."—George W. Bush, Declining to answer reporters' questions at the Summit of the Americas, Quebec City, Canada, April 21, 2001

[Ninong]

Originally posted by PerryinCA:

Of all those (which are but a few of the ones I have been reading recently) none got my attention more than "Temperature elevations above summer ambient, but still below the bleaching threshold, can impair growth and reproduction."

That is exactly what Ron is saying in his article on temperature and salinity.

Here is the exact excerpt:

"Prosser, C. L. ed. 1991. Environmental and Metabolic Animal Physiology. Wiley-Liss, Inc. New York, NY. 578pp .

It details how and why animals die at lower as well as upper lethal limits, and how normal behavior and metabolism stops well before those limits are reached."

Incidentally, this is the basis for all the recommendations of 74-78F in reef tanks--to hold down normal growth and metabolism and thereby make the tank less prone to disease and parasites, and avoid problems associated with the amount of food that would be necessary to support normal metabolism. Some of the authors who were recommending mid 70's Fahrenheit for reef tanks several years ago are now recommending high 70's. Julian Sprung now recommends 76-80F as ideal; this is higher than his recommendation in TRA-1.

Ninong [img]/ubb/biggrin.gif[/img]

P.S. - I still think you should shoot for 81F as a reasonable compromise. [img]/ubb/wink.gif[/img]

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"Neither in French nor in English nor in Mexican."—George W. Bush, Declining to answer reporters' questions at the Summit of the Americas, Quebec City, Canada, April 21, 2001

[Ninong]

Originally posted by PerryinCA:

Well about half of those I can throw out and not read as they pertain to species that I don't have, or look to me to simply be part of "list" of references made to overwhelm possible readers.

Sorokin lists approximately 2,000 references in the back of his book, even down to page numbers. I think they borrow each other's lists. [img]/ubb/wink.gif[/img]

If Sorokin's info is valid, then Ron is preaching to keep our reefs at the "upper limits". Wouldn't the median be most ideal?

I believe Ron is preaching a range that he considers to be optimum--not too high and not too low. [img]/ubb/biggrin.gif[/img]

For one, not all coral come from that high of temp, 2 why flirt with disaster by keeping tanks at the upper limits?

An awful lot of SPS that is collected for the hobby is adapted to high temps and even exposure at low tides because they have a tendency to collect the stuff in very shallow waters where it is easiest to get at during low tide. You should not flirt with disaster by keeping tanks at the upper limits. Ideally, you should keep them at the optimal temperature range if it is possible to do so without undue risk.

What exactly is considered a "long-term" exposure to Sorokin? Day, week, month?

I believe "long-term" exposure in the literature refers to a matter of weeks.

Here's a couple that prove some interesting reading:

Interesting, but Bahamian, Hawaiian, and Jamaican reefs are all high latitude reefs which are not typical of central Indo-Pacific reefs, which supply most of the animals to the hobby.

Here's an interesting excerpt: sites that temperatures of 33-35 caused mass bleachings and coral death.

Yes, prolonged exposure to temps of 33-35C (90-94F) will definitely do that. My understanding of Sorokin is that he is saying that stress starts at long-term exposure to temps of 89F and becomes serious enough to initiate bleaching with long-term exposure above 89-92F. I am sure that you could get serious bleaching with even lower temperatures if you also threw in some other complications like extremely low tides or falling sea levels.

Here I quote fromt the abstract: "Bleaching can be
induced by short-term exposure (i.e. 1-2 days) at temperature elevations of 2 degree C to 4 degree C above normal summer ambient or by long term exposure (i.e. several weeks) at elevations of 1 degree C to 2 degree C. Corals in both tropical and subtropical locations live at temperatures close to their lethal limits during the summer months.

Yes, elevations of 2-4C (3-7F) above normal summer temps for even a couple of days can induce bleaching, particularly if there are other complicating factors. Long-term exposure to elevations of as little as 1-2C (2-4F) can also cause problems.

Ninong [img]/ubb/smile.gif[/img]

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"Neither in French nor in English nor in Mexican."—George W. Bush, Declining to answer reporters' questions at the Summit of the Americas, Quebec City, Canada, April 21, 2001

[Kalkbreath]

I think we need to explore the temp. vs. light source aspect of coral bleaching a bit more if we are to truly understand this issue..( Steve Tyree uses 20,000k for instance) If I place my hand just under the water, below a 400 watt MH my skin still burns, but the water temp is still 79 degrees? Yet if I go swimming and do the same, with my hand just under the surface no burn, but much greater PAR and UV? When we try to compare our little glass boxes to the Great Blue Sea, we are failing to admit they are not the same..." I knew the Ocean personally, and you my friend,(looking at my tank).....are no OCEAN..."

[Ninong]

Perry ~

You may find Eric Borneman's answer to the reef tank temperature question interesting. He gives a recommendation (which he highlighted in bold text in his book) along with a cautionary warning.

Excerpt from p.348, Aquarium Corals: Selection, Husbandry, and Natural History by Eric H. Borneman (2001) --

"Although it has been recommended in the past that aquarium temperatures should be maintained between 24-27C (75-80F), the natural temperature of many Indo-Pacific reefs, especially in the shallow areas where most corals are collected, is higher than 27C (80F).

It had always been assumed that temperatures lower than natural levels prevented the rapid growth of unsightly algal films on the aquarium glass and lessened the proliferation of problem hair algae. Recent trends favor maintaining somewhat more natural reef temperatures of 27-29C (80-84F). The reasoning behind this increase is that the entire metabolism of the tank is raised, including those of the microbial community, detritus-processing organisms, and herbivores. Furthermore, it is a more natural temperature for many reef animals. The increased rates of calcification at these temperatures should, therefore, not be offset by increasing algae growth, unless the system is mismanaged.

There are some negative aspects to increased temperatures, however. Although higher ambient temperatures that are in line with normal reef temperatures may be beneficial, it has also been shown that increasing temperatures above those to which the corals are acclimated may decrease autotrophic abilities and trigger temperature-induced bleaching or death. Thus an accidental rise of a few degrees from a broken or misadjusted heater or chiller could have dire results. Even in nature, prolonged exposure to high or low temperatures can have serious consequences. Tropical corals live within about 2.8C (5F) of their upper lethal limit, yet temperatures below that range cause 'profound physiological changes, notably in respiration and photosynthetic rates' (Davies, 1992). The oxygen saturation level at higher temperatures is also lower, although good water movement and/or the use of a protein skimmer is sufficient to maintain oxygen levels at or near saturation."

Ninong [img]/ubb/smile.gif[/img]

P.S. - Here is Eric's adaptation of that same study of 1,000 coral reefs that everybody keeps quoting (Kleypas et al., 1999) --

Temperature
Average of all reefs tested: Minimum 21C (70F), Maximum 30C (86F), Average 28C (82F).
Reef with lowest temperatures: Minimum 16C (61F), Maximum 28C (82F), Average 25C (77F).
Reef with highest temperatures: Minimum 25C (77F), Maximum 34C (93F), Average 30C (86F).

According to Eric, the Philippines are unusually warm at 31C (89F).

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"Neither in French nor in English nor in Mexican."—George W. Bush, Declining to answer reporters' questions at the Summit of the Americas, Quebec City, Canada, April 21, 2001

[Ninong]

Hi Kalkbreath, welcome to Reefland! [img]/ubb/biggrin.gif[/img]

Ninong [img]/ubb/smile.gif[/img]

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"The Senate needs to leave enough money in the proposed budget to not only reduce all marginal rates, but to eliminate the death tax, so that people who build up assets are able to transfer them from one generation to the next, regardless of a person's race."—George W. Bush, Washington, D.C., April 5, 2001

[PerryinCA]

Ninong, I think we took tw different roads to get to the ame place.[img]/ubb/smile.gif[/img]

I recognized that some of my refernces were from higher Lat. reefs, but the reef temperature isn't what I was using them for. All I was trying to show was that in some cases its not "just fine" to let you tank get into the upper 80's, and it shouldn't be taken with a grain of salt. Some of those bleachings had increases of only a few degrees F above normal and the product was wide spread bleaching (and 80% of the bleached corals lost).

I think that we are pretty much in agreement over tank temp... Taking Borneman's numbers and getting the mean of the averages I get 81.5, which is what I feel would be an ideal number. I think anything higher as a base line and you flirt with disaster.

-Perry

[Ninong]

Perry, check out this interesting discussion on oxygen saturation by Rob Toonen: http://www.reefs.org/library/article/r_toonen14.html

Ninong [img]/ubb/smile.gif[/img]

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"The Senate needs to leave enough money in the proposed budget to not only reduce all marginal rates, but to eliminate the death tax, so that people who build up assets are able to transfer them from one generation to the next, regardless of a person's race."—George W. Bush, Washington, D.C., April 5, 2001

[Minh Nguyen]

I think the problem in your case is the temperature normally peak at 82, then spike and peat at 87 (? for a few days). I can tell you that my tank temperature normally peak out at 87 everyday in the summer, I don't have any problem with this. I have a very accurate digital thermometer that keeps track of daily peak and trough. Every night, my tank lower down to 80 in the summer and 77 in the winter.
I don't aim to have my tank peak out at 87, just that I don't have the place for a chiller, and I don't think placing a chiller under the stand is a very good idea. I wasted too much energy pump heat in a circle. I am re-build my tank now. I will change the tank lay out. I will have the top of my tank cabinetry open, and I will keep the pumps (two Aqua Sea 4700 and one Ampmaster 300) and light ballast (4 400 W MH) in the cabinet nest to the tank instead of under the tank. I think I will be able to keep my tank below 84 even in the mid of Texas summer with fans. I will be very happy if my tank doesn't get hotter than this during mid summer.
Minh

[scubadude]

Gia,

Do you still have your tank outside? What do your temps range and when/if do you notice bleaching (I seem to remember something a while back about your tank having some problems and you had to tear down cuz of heat?). Also would like to know what species you are/aren't having problems with bleaching on.

Minh,
So correct me if im wrong but your saying cuz your tank peaks at 87 everyday in the summer that your corals have adapted (and obviously thrived) in this range? also have you noticed any specific corals decline/incline as far as the high temps in summer?

Great thread!

Rocky

[dougc]

I have seen widely variable responses of corals to heat in my tank. I had no chiller, so sometimes the temps would get up to about 84 on a hot summer day and cool down to 80 at night. I had one acro that always receded from the base during these warm episodes. This acro would recover when cooler weather hit. Other acros and montis seemed to have no problem with this pattern.

Then came the stuck heater episode. Having gotten lazy about checking the tank religiously, my first indication of a problem was noticing that a montipora digitata looked lighter than normal. This got me looking for a cause and I quickly established that my thermometer read 87. I don't know how long the temperature was elevated before that or what the peak was, but I lost several corals, including most of my montiporas and a staghorn. It was all downhill from there. The tank completely crashed and burned a few months later and I had to break it down.

I am getting ready to start up a new tank now (after 6 months with nothing) and this tank will have a chiller and an AquaController to help me keep the temperature in a narrower range and to squawk if anything goes wrong. Not every coral will bleach when the tank gets warm, but some will. I guess you could run a tank with wide temperature swings and let nature select the corals that can survive it, but I am not happy with that approach.

[Minh Nguyen]

Gia,
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Minh,
So correct me if im wrong but your saying cuz your tank peaks at 87 everyday in the summer that your corals have adapted (and obviously thrived) in this range? also have you noticed any specific corals decline/incline as far as the high temps in summer?

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The one problem I have is with Pocillopora, and Stylophora. Some time I also ahve problem with new frags from other reefers's tank. Esspecialy those that keep them at lower temperature.
I got a 1 HP chiller in my tank now and I keep the tank temperature peak at 82.5
Minh