Aquarium Temperature

[airinhere]

Just like with any other piece of eclectic machinery reefkeepers might hook up to their tanks, a chiller has to have a purpose if someone was to justify that kind of purchase. Not just the cost of the chiller, but the cost to run it, the heat, the size...

Most people do not keep exotic acros or other SPS that need to have completely inert tank parameters. Their water quality must remain rock steady and that includes temperature. Again, there are corals out there that need this kind of enviroment to survive. But if you are asking about temperature, odds are you do not have any of those corals.

The rest of us keep what are considered to be fairly hardy species of coral. often gathered from all over the globe, but still rather robust organisms. My preference to keep my tanks at a certain temp is a function of what temp my tanks remain at after I light them up and turn on my fans. I could easily see someone whose tanks remain a few degrees higher than mine having just as much luck keeping corals as I have.

However, when someone asks what temp to keep their tank at, I have to consider their question to be coming from a new reefkeeper who is looking for basic information. This topic is hotly debated by even the most advanced aquarists so anyone can reason that the answer is not always as simple as "keep it around 80F".

I give my answer knowing that corals survive all sorts of terrible conditions but sometimes expire from minor fluctuations. Understanding that the person asking the question is not looking for a philisophical debate, I keep my answers in "safe" territory.

Essentially, I provide an answer that is going to ensure the longevity of his corals with the greatest margin for error.

I didn't come up with this concept. I was advised long ago to refrain from posting anything that could get someone into trouble later on.

The person asking this question has started pouring their time and money into their tank, and it is only fair of me to keep from advising them to do "risky" things.

besides, they will eventually learn all about the "risky" things we can really get away with in our tanks.

Sometimes with amazing results.

 

[mxett]

<a href=showthread.php?s=&postid=11017632#post11017632 target=_blank>Originally posted</a> by airinhere
However, when someone asks what temp to keep their tank at, I have to consider their question to be coming from a new reefkeeper who is looking for basic information. This topic is hotly debated by even the most advanced aquarists so anyone can reason that the answer is not always as simple as "keep it around 80F".

I give my answer knowing that corals survive all sorts of terrible conditions but sometimes expire from minor fluctuations. Understanding that the person asking the question is not looking for a philisophical debate, I keep my answers in "safe" territory.

Essentially, I provide an answer that is going to ensure the longevity of his corals with the greatest margin for error.

So, lets play hypothetical ( one of my favorite games), imagine I am a newbie. I want to keep some acros and some lps, I'm using MH's whih will probably mean I get into the low 80's late in the day, especially in the summer, maybe even the odd day of 85f. Do you recommend I get a chiller? Remember I have a finite budget being blue collar and all

 

[greenbean36191]

I am not aware of anyone saying that the cooler water (mid 70's) is even potentially dangerous for any of our corals. However, much research has pointed to higher temps (mid 80's) as being dangerous to corals.

Colder than normal temps have the same effects as warmer than normal (increased disease, metabolic stress, bleaching, etc.) and are well documented in the primary literature. Excessive cooling hasn't been a problem for the reefs as of late though, and hasn't been covered in the popular media.

Are they advocatng keeping corals at temperatures known to be hazardous to the corals? What species are they talking about?

I'm advocating keeping corals within the average range for reefs worldwide and near the temps where the greatest coral diversity occurs. As you pointed out we have animals from all over the world and we can't cater individually to all of them. Does it make more sense to pick near the edge of their limits or the center as your recommendation? I think most people with a background in ecology would pick the center of diversity.

Their water quality must remain rock steady and that includes temperature. Again, there are corals out there that need this kind of enviroment to survive. But if you are asking about temperature, odds are you do not have any of those corals.

Those corals are what we call in the business "extinct." I wouldn't worry too much about trying to meet their needs.

I give my answer knowing that corals survive all sorts of terrible conditions but sometimes expire from minor fluctuations.

The idea that fluctuations kill corals is a self fulfilling prophecy. If you acclimatize your corals to stable conditions because you're afraid fluctuations will kill them, any subsequent small fluctuations can kill them quite easily. When they aren't acclimatized beforehand though, it doesn't happen. At least two of the articles I listed delve into the importance of acclimatization to inducing thermal stress in corals.

Essentially, I provide an answer that is going to ensure the longevity of his corals with the greatest margin for error.

Like most people in the hobby, you're under the erroneous impression that keeping temps cooler or more stable provides for a larger margin of error. The width of the margin of error is determined by the amount of fluctuation, not by the average temp you keep the tank. Small fluctuations give a small margin of error and large fluctuations give a larger margin. Where that margin is centered is essentially a sliding scale centered around the average temp. A tank that sees 76 constantly has no more of a margin of error than a tank that sees 83 constantly. On the other hand a tank that ranges from 80-86 has a larger margin of error than a tank that ranges from 76-78 even though the first tank is warmer.

It's important to realize that the metabolic reactions in corals and their zoox rely on enzymes to work efficiently. Enzymes only work well under narrow temperature conditions and outside of those conditions metabolism starts to bog down. Organisms get around that by making multiple forms of each enzyme that are optimized for different temps. When one form stops working well, a different form picks up the slack. What you end up with is a mix of enzyme forms, only a few of which are useful at any given temperature. Biology doesn't favor waste though, over time more energy is put into making the forms that are used more and less into producing the forms that are needed less. That's great as long as the temp stays stable. If it changes though, you better be able to make the right enzymes quickly or you're in big trouble.

The variation or lack thereof induces very real physiological changes in the corals by making them change the proportions of their enzyme mix (acclimatization).

 

[nathenvan]

SPS are the problem, most LPS and soft really don't care once they are used to the condition of your tank. Mine is 86 in the day and 78 at night. just my 2 cent

 

[mxett]

sps arent a problem. I have six reasonable sized colonies in my 90g and they see between 79 and 85f regularly. All are colourful and growing. Last time I visited the great barrier reef I noticed acros and other sps mixed with softs as well, all with the same variation in natural seawater temeratures.

 

[airinhere]

And the debate rages on....

All you new guys better start getting used to this. The whole hobby is stacked full of very widely debated topics. Try asking about deep sand beds vs shallow sand beds. Or compatability of tankmates. Or what lighting is the best? What temperature color of lights are most effective? Wet skim or dry skim?

Pretty much everything we do.

Gonna have to learn to read, comprehend and make good decisions based off what you learn here.

Happy reefing.

 

[m2434]

<a href=showthread.php?s=&postid=11024081#post11024081 target=_blank>Originally posted</a> by airinhere
And the debate rages on....

The whole hobby is stacked full of very widely debated topics.

The whole hobby is full of debates and thats why I love it and no it's not because I like to argue. This hobby is in a way a portal into a new frontier. We really don't no much about the ocean, it is the most mysterious place on earth. With this hobby, I am able to keep and marvel at a piece of it right in my own home. The reason we debate is is because we really don't know much, if we did, we wouldn't debate and I'd probably get board with the hobby.

 

[elegance coral]

Greenbean, can you explain how cooler temps can cause bleaching? I have never heard of this and don't understand the mechanics behind such an event.

I agree with the people here that have said the individual species is very important when talking about temp. Even the area of collection for the individual within a given species. My first Elegance was surely collected from very shallow/worm waters. It survived temps into the 90's on many occasions. The newer Elegance corals from the Indo Pacific are collected from much deeper/cooler waters. At temps around 79 to 80 they begin to swell. I have had them for almost 2 years and can not get them acclimated to higher temps. I have two Australian Elegance corals that most likely came from shallower/warmer waters and they can handle temps into the higher 80's with no problem.

I believe That the amount of light the coral is exposed to plays a major role in its ability to withstand higher temps. If a coral is exposed to intense lighting that is near its maximum level a slight increase in temp can cause bleaching. A coral that is exposed to light that is not to intense can withstand higher temp spikes without bleaching.

With the abundance of evidence we have that shows higher temps can be deadly to coral we should make the effort to keep our tanks running cooler. Just because a few hobbyists have experienced temps above 86, or higher, without bleaching is not evidence that these temps are safe.

 

[jay24k]

During the summer mine is from 82 to 86. I haven't lost a coral yet. If it hits 87, I turn the lights off. During the winter months, it stays around 78 to 81.

I think people are getting confused just because they are divers. Not every place is going to be the same. In Venezuela where I dove, at approximately 36 feet, the water temp would drop from the 80s to freezing cold during the mid summer. In other areas, I never noticed it all suggesting it was much deeper. I generally stay above 60 to 70' when diving.

However, since I haven't experienced diving in many of the reefs, I don't see how I can put any two cents in. I think Greenbean from his experience would know this since he is gone fairly often doing this.

 

[greenbean36191]

Greenbean, can you explain how cooler temps can cause bleaching? I have never heard of this and don't understand the mechanics behind such an event.

Bleaching is a general response to lots of different stressors, not just hot or cold. AFAIK, no one knows the mechanism for bleaching at low temps, which isn't surprising since the mechanism is poorly understood for all causes, including bleaching under high temps. It's unlikely the mechanism is the same under cold conditions though since under high temps excessive production of O radicals is to blame.

The newer Elegance corals from the Indo Pacific are collected from much deeper/cooler waters.

Again, the average drop in temp is only ~2F for the first 90ft on the reef and variation only increases with depth. If these corals really are coming from deeper water, you wouldn't expect to see an increased sensitivity to normal captive temps. AFAIK no one has shown any link between the syndrome these corals suffer from and temp.

I believe That the amount of light the coral is exposed to plays a major role in its ability to withstand higher temps. If a coral is exposed to intense lighting that is near its maximum level a slight increase in temp can cause bleaching. A coral that is exposed to light that is not to intense can withstand higher temp spikes without bleaching.

That's correct. High lighting decreases the tolerance to temperatures outside of the norm.

With the abundance of evidence we have that shows higher temps can be deadly to coral we should make the effort to keep our tanks running cooler. Just because a few hobbyists have experienced temps above 86, or higher, without bleaching is not evidence that these temps are safe.

It's important to make the distinction between higher within the normal range and higher outside of the normal range. Higher temps within the norm don't cause bleaching. Higher (or lower) temps outside of the norm can depending on how far outside they fall and for how long.

Again, we can't cater our tanks to each animal, so we have to do what's best for most of them by picking a common middle ground. We can't simply cater to the least common denominator because most corals don't appreciate water that's in the low 60s or low 70s just like most don't like 90s. 86 is the yearly max for the majority of the worlds coral reefs (SD of <.75 degrees) and is a safe maximum temperature for the majority of animals we keep. A bit above 76 is the average minimum, but the standard deviation is a lot bigger (3.24 degrees). That means roughly half of our animals will be fine down to 76, but most of the other half will be somewhere between 73 and 80. If you're really anal about exposing your animals to the least risk from temperature, you should be keeping your tank between 80 and 85, not in the upper 70s. Realistically though, we know that 76-86 is safe for the majority of animals with 82 being the overall average, the temp where the greatest amount of coral diversity occurs, and slightly lower than the temps most corals see optimum growth.

 

[elegance coral]

<a href=showthread.php?s=&postid=11025662#post11025662 target=_blank>Originally posted</a> by greenbean36191
Bleaching is a general response to lots of different stressors, not just hot or cold. AFAIK, no one knows the mechanism for bleaching at low temps, which isn't surprising since the mechanism is poorly understood for all causes, including bleaching under high temps. It's unlikely the mechanism is the same under cold conditions though since under high temps excessive production of O radicals is to blame.


I agree that corals react to lots of different stressors, but only know of three that will cause the discharge of their zooxanthellae. Light, heat, and darkness. Can you point me to any information that would suggest that a coral will bleach due to cold temps? I agree that cold temps could be very stressful, but don't understand how it could cause bleaching.


Again, the average drop in temp is only ~2F for the first 90ft on the reef and variation only increases with depth. If these corals really are coming from deeper water, you wouldn't expect to see an increased sensitivity to normal captive temps. AFAIK no one has shown any link between the syndrome these corals suffer from and temp.



It has been reported that these Elegance corals are collected at depths of over 100 feet. Even if we say that the water temp at these depths is only a few degrees cooler than the shallows, we can't ignore the "car in the parking lot effect". The temp within a coral in direct sun light can climb higher than the water around it. This effect is virtually nonexistent at greater depths.

What would it take to show a link between the syndrome these corals suffer and temp? I lost 4 of these Elegance corals when my temp briefly climbed to the high 80's. Through July and August my temp would approach 80. Every time this happened my corals began to swell. Frozen water bottles in the sump would correct this problem and they would stop swelling.

 

[jiperalta]

IF my water temp is consistently 79 oF, what kind of tang can I keep in my 20-gal tank?


(i keed, i keed...)

 

[greenbean36191]

I agree that corals react to lots of different stressors, but only know of three that will cause the discharge of their zooxanthellae. Light, heat, and darkness. Can you point me to any information that would suggest that a coral will bleach due to cold temps? I agree that cold temps could be very stressful, but don't understand how it could cause bleaching.

Virtually any review of bleaching will cover some of the known causes. I don't have them here in front of me, but I think the first paper I mentioned and probably the last two cover cold bleaching.

Some others I have written down are:
Saxby T., Dennison W.C, and Hoegh-Guldberg O. 2003. Photosynthetic responses of the coral Montipora digitata to cold temperature stress. MEPS

Hoegh-Guldberg O., Fine M. 2004. Low temperatures cause coral bleaching. Coral Reefs 23:3 444.

Hoegh-Guldberg O., et al. 2005. Coral bleaching following wintery weather. Limnol. Oceanogr. 50:1 265â€"œ271.

There was also a cold snap recently that caused bleaching on the GBR that you should be able to find some info about.

What would it take to show a link between the syndrome these corals suffer and temp?

I can't think of a good way for a hobbyist to show a strong link. Correlations help, but there are too many variables and potential artifacts to really make a strong argument.

If I was doing it in the lab, my first step would be to take temp readings where the corals are coming from. Then I'd do metabolic measurements at temps simulating their natural habitat and start cranking things up, looking for changes in the p:r ratio (which indicates stress). Finally, I'd check for any unusual pathogens and possibly run the same experiment again in the presence of broad spectrum antibiotics.