Help with Halides for 72g

[Ninong]

There is also nothing wrong with keeping your temp between 77-80. lately the trend seems to be to keep it below 80. JMHO

What's trendy in Montana can cost a lot of money to achieve in Dallas.

[scottfaulkner11]

hahaha very true, my ac has a hard time cooling the house below 77 (especially cost wise) when its 100+ outside

[charlie]

What's trendy in Montana can cost a lot of money to achieve in Dallas.

It isn't only trendy in Montana George.

[returnofsid]

77-80 is pretty much a universal choice for most reef tanks. It more closely matches the natural temperatures of the reefs, except in the Red Sea, where they're slightly warmer.

It also gives you more room for sudden spikes temperature, during the hottest days of summer. 80-83 sure doesn't give you much room, in the event of a heat wave, such as we're having in Spokane right now. Granted, it's not a large heatwave, probably get up to 94 today, but enough to make it difficult to keep my 75 below 82 degrees. I've already noticed some SPS corals suffering from the higher temperatures.

Another thing to keep in mind, with higher temperatures, is that fish' metabolic rates increase, meaning they breath more and consume more oxygen. This creates a problem, because at higher temperatures, there is less dissolved oxygen in the water. Oxygen is less soluble at higher temperatures. Also, as things decompose in our tanks, they create ammonia. At higher temperatures, this happens faster. Not only do things decompose faster, ammonia is produced slower and in lower quantities, at lower temperatures.

[Ninong]

77-80 is pretty much a universal choice for most reef tanks. It more closely matches the natural temperatures of the reefs, except in the Red Sea, where they're slightly warmer.

I don't agree with your statement that "77-80 is pretty much a universal choice for most reef tanks" but that's a subjective statement and we're all entitled to our own opinion. However, I will disagree with your claim that 77-80 "more closely matches the natural temperatures of the reefs, except in the Red Sea." That statement is factually incorrect.

I suggest you visit the AIMS and NOAA sites and check their real-time buoy readings for various tropical reefs. AIMS even has readings at varying depths for some stations.

I'm sure we all agree that Indonesia is the ideal environment for coral reef animals as proven by their unmatched population density and diversity. Do you really believe that 77-80F "closely matches the natural temperatures of the reefs" in Indonesia?

Sea Temperatures in Indonesia

This month's water temperatures:
Average sea temperature 29.3C (84.7F)
Maximum sea temperature 32C (89.6F) Paloh
Minimum sea temperature 27C (80.6F) Bali

Long term water temperatures:
Average sea temperature 29.5C (85.1F)
Maximum sea temperature 32C (89.6F) Paloh
Minimum sea temperature 27C (80.6F) Kupang

I don't see anything even closely resembling 77-80F (25-26.7C) anywhere on there and Indonesia has the most ideal reef conditions on the planet.

The average water temperature of 1,000 corals reefs from all over the world is 81.7F (27.6C) according to a study published by Dr. Joan Kleypas in 1999 and that included reefs where corals are just barely present because the average temperature is 76.2F (24.6C). That was the lowest average temperature found on any of the 1,000 reefs studied. The highest average temperature was 86.4F (30.2C). The average maximum temperature was 85.1F (29.5C), lowest maximum was 82.8F (28.2C) and the highest maximum was 93.9F (34.4C).

I think it is much more informative for our purposes to look at the water temperatures found on reefs where corals flourish than to include reefs in areas farther from the equator where they barely exist, but even including those reefs in the study, the average temperature was 81.7F (27.6C).

The reason I would avoid looking at the Red Sea as a model is that water temps there, especially in the northern Red Sea, swing quite a bit between the seasons. The Red Sea has higher maximums than Indonesia but it also has lower minimums. And the salinity in the Red Sea is the highest found on any coral reefs anywhere in the world: 39-41 ppt.

It also gives you more room for sudden spikes temperature, during the hottest days of summer. 80-83 sure doesn't give you much room, in the event of a heat wave, such as we're having in Spokane right now.

Corals will experience distress whenever the maximum temperature spikes as much as 3-4 degrees Fahrenheit above the range to which they have been acclimatized. Therefore, if your corals have been maintained at a constant temperature of 78F with the help of a chiller and you experience a power failure that lasts for several days, causing your temperature to rise to 85F, you are likely to lose some corals. On the other hand, if your corals are acclimatized to a temperature of 83F, they can easily manage temperature spikes to 85-86F and will only experience distress at temps above that.

It's not the high temperature that causes the problems so much as the difference between the temperature they are used to and the temperature spike. A spike of 4-5 degrees Fahrenheit above the normal daily maximum is going to cause problems even if you maintain your aquarium at lower temps, especially if the corals are not used to daily temperature swings.

Corals in nature live right at the threshold of disaster but that threshold is different for different reefs because it all depends on the temperature range that the corals are adapted to. The problem comes in when the maximum temperature gets more than 2C above the normal maximum for extended periods of time (3 weeks or more). Corals on reefs in the Bahamas have adapted to a much wider range of temperatures than corals in Indonesia because the temperature there varies substantially from one season to the next. Indonesia is on the equator. Temperatures there do not vary much from month to month and there are virtually no seasons. Corals in Indonesia would die off if subjected to the temperature ranges experienced by corals in the Bahamas. They wouldn't be able to take the lower winter temps because there are no winters in Indonesia.

Granted, it's not a large heatwave, probably get up to 94 today, but enough to make it difficult to keep my 75 below 82 degrees. I've already noticed some SPS corals suffering from the higher temperatures.

SPS corals in nature are capable of handling extreme swings in temperature and very high maximum temperatures as long as those temps do not exceed their normal range by more than 2C for extended periods of time. In fact, SPS corals that are found at shallow depths are more capable of withstanding extreme temperatures than your typical corals that are found at 10m depth because they are more adapted to extreme swings.

Another thing to keep in mind, with higher temperatures, is that fish' metabolic rates increase, meaning they breath more and consume more oxygen. This creates a problem, because at higher temperatures, there is less dissolved oxygen in the water. Oxygen is less soluble at higher temperatures. Also, as things decompose in our tanks, they create ammonia. At higher temperatures, this happens faster. Not only do things decompose faster, ammonia is produced slower and in lower quantities, at lower temperatures.

It is a fact that metabolic rates slow down at lower temperatures. Therefore, if one wants to provide unnaturally low water temperatures as a way to reduce growth to below what would be natural, that's one way to do it.

We know from studying coral skeletons that corals grow best at temps of about 84F and that growth slows substantially at temps below 79F. That's a fact.

If you want to argue that it is in some way easier to run a low temp, low energy, slow growth reef aquarium at 77-80F than to run one at natural temperatures with natural growth rates, go right ahead. You just can't claim that "77-80 more closely matches the natural temperatures of the reefs" because that statement isn't even close to being correct.

[charlie]

Why don't we just post a poll up to see what people here keep their reef temps at??????

[Ninong]

Charlie, we have done that three or four times already over the years, back when we had much more active participation than we have right now. As a matter of fact, one of those polls keeps popping back up from time to time because I have seen it on the board within the past few months.

[Ninong]

Rocky started this poll in 2001. That's definitely not a scientific sampling of reef hobbyists but, as you can see, the most popular answer was 78-82F. I know there were other more recent polls.

I'll go check and see if RC has a poll with a larger sample.

P.S. -- It's difficult to find anything on RC because they moved so much of their stuff to the archives, which are separate from the regular forum. I did manage to find this poll from three years ago but the participation wasn't all that great.

Rocky posted his poll with overlapping ranges (e.g., 74-78 got 7%, 76-80 got 27%, 78-82 got 47% and 80-84 got 20%).

In the RC poll, the most popular answer was 80-81 with 43%, next came 78-79 with 25%, followed by 82-83 with 15% and 84-85 with 7%.

As unscientific as those polls are, I believe it is obvious that 77-80 is not a universal choice. Quite a few of the hobbyists who responded in those two polls keep that reef tanks above that range. In fact, in the RC poll, 64% of those responding to the poll keep their reef tanks above 80F. That's not all that different from Rocky's poll. In Rocky's poll, 34% of the people keep their tanks below 80F. We know that because the next range up is 78-82F, so anyone who checked that box allows his tank's temperature to rise to 81-82F. I have no idea why Rocky used overlapping ranges.

The main point of my response was that it is factually incorrect to say that 77-80F is closer to natural reefs temps than my preferred range of 80-83F. As I have said in several threads, my ideal temperature is 82F. We already know that you and Sid prefer 77-80F.

Corals in nature can adapt to a wide range of temps and a wide range of average temps; but if you want to know what the IDEAL reef temps really are, look at Indonesia. Don't look at Hawaii or the Bahamas. Or the Red Sea, which is at the extreme limit of survivability for both maximum salinity and temperature.

[charlie]

We could probably sit and argue, discuss, this til the cows come home.

Rocky posted his poll with overlapping ranges (e.g., 74-78 got 7%, 76-80 got 27%, 78-82 got 47% and 80-84 got 20%).

If you look at this, it looks to me as tho most of the people, myself included, keep their systems between 76 and 82, with 82 being the absolute high end when your lites have been on all day. We cannot dispute the fact that most reefs are warmer than we keep our tanks. I also agree with Michael in that trying to keep our tanks on the lower end, does give us more wiggle room if the temps spike.

I think it all runs down to the old addage, there is more than one way to skin a cat, so to speak, and some folks just use the lower end to achieve their own particular end.

That is about as diplomatic as I can be this early without my first cup of coffee yet.

[returnofsid]

While the natural reefs may be a bit higher than we keep our tanks, water on the natural reefs is also MUCH more oxygenated. In fact, we could never keep our reef tanks as oxygen rich as the ocean. This causes a problem, when keeping our tanks at higher temperatures. At higher temperatures, the dissolved oxygen is at a much lower rate, than at lower temperatures. This becomes a problem because, at those same higher temperatures, our fish's metabolic rate increases, including respiratory rate. The respiratory rate increases, requiring more oxygen, yet less oxygen is in the water.

When I made mention of matabolic increases, in my earlier post, it had absolutely nothing to do with artificially stunting growth. I was mentioning it only in the context of how higher temperatures can negatively effect our fish, due to decreased dissolved oxygen, increased respiration, and also increased ammonia toxification, due to increased speed of organic decomposition and increased ability for the creation of ammonia, which is built up slower and slightly cooler temperatures.

BTW, are the cows home yet? Back to the original question of this post, I'd agree that 250MH or T5HO would be a much better choice, than 150MH for the tank in question.

[Ninong]

While the natural reefs may be a bit higher than we keep our tanks, water on the natural reefs is also MUCH more oxygenated. In fact, we could never keep our reef tanks as oxygen rich as the ocean. This causes a problem, when keeping our tanks at higher temperatures. At higher temperatures, the dissolved oxygen is at a much lower rate, than at lower temperatures. This becomes a problem because, at those same higher temperatures, our fish's metabolic rate increases, including respiratory rate. The respiratory rate increases, requiring more oxygen, yet less oxygen is in the water.

When I made mention of matabolic increases, in my earlier post, it had absolutely nothing to do with artificially stunting growth. I was mentioning it only in the context of how higher temperatures can negatively effect our fish, due to decreased dissolved oxygen, increased respiration, and also increased ammonia toxification, due to increased speed of organic decomposition and increased ability for the creation of ammonia, which is built up slower and slightly cooler temperatures.

BTW, are the cows home yet? Back to the original question of this post, I'd agree that 250MH or T5HO would be a much better choice, than 150MH for the tank in question.

I can't believe we are still discussing the question of reef tank temperatures but I hate to allow this sort of misinformation to go unchallenged.

First you said that "77-80F is pretty much a universal choice for most reef tanks" after I had previously posted that "A temperature range of 80-83 F is fine for a reef tank. It's only when it starts to go over 84 F that you can run into problems." You went even further by saying that "77-80F more closely matches the natural temperatures of the reefs."

You could have said "many people recommend 77-80F for reef tanks" and I would have let that slide. I believe that more people keep their reef tanks above 80F than below 80F but, in either case, that's a matter of personal opinion and everyone is free to make up his own mind on what temperature he thinks is best. So that statement is really just a gross exaggeration because 77-80F is not "pretty much a universal choice" for reef tanks any more than Delbeek & Sprung's recommendation in TRA-1 that 74-76F is the ideal reef aquarium temperature, because it clearly is not the ideal reef aquarium temperature.

I believe we have proven conclusively that 77-80F does not more closely match natural temperatures of the reefs than my recommendation of 80-83F. My ideal temperature recommendation is 82F but I believe a range of 80-83F is fine. For those folks who have problems with temperature control, then they will have to do whatever is best to allow for their equipment limitations.

Now you are claiming that "natural reefs may be a bit higher than we keep our tanks." Well, if you're still talking about 77-80F, then natural reefs are a lot higher.

Then you went on to offer the misguided advice that oxygen saturation is the reason that we should not keep our tanks at reasonable temperatures (e.g., 82F, which is the ideal temperature that I always recommend). You can't be serious? You made the grossly exaggerated statement that "At higher temperatures, the dissolved oxygen is at a much lower rate, than at lower temperatures." Where did you get that idea?

You are implying that my recommended temperature range of 80-83F, which I previously posted was "fine," is somehow going to cause problems because of a "much lower" rate of oxygen saturation. That's not true. This sounds like the sort of advice handed out free of charge at your typical LFS.

Oxygen saturation in mg/l at a salinity of 35 ppt.

25C (77F)-----6.9mg/l
28C (82.4F)---6.6mg/l
30C (86F)-----6.4mg/l

As you can see, there is only a slight difference in oxygen saturation between 77F and 82.4F. Your conclusion that this slight difference in oxygen saturation is a problem for fish is misguided. As Walter Adey's measurements of his ATS-based tanks at the Smithsonian proved, it is not the oxygen concentration itself that is important but rather the EXCHANGE rate of the oxygen.

Natural seawater in areas around natural reefs is generally 95-110% saturated with oxygen, and greater than 60% of areas measured are at 100% saturation. On the reefs of St. Croix, night time oxygen levels range from about 5-6.5 mg oxygen/l, and daytime levels rise to around 7.5-9 mg/l depending on the reef and location.

Protein skimming and turbulent water flow (powerheads, etc.) provide more than enough exchange to take care of the respiratory needs of your animals. Normal exchange rates in the average reef aquarium are about 4-6g of oxygen per square meter per hour. That's more than enough to meet the needs of a fully stocked aquarium.

Even if you look at your lowest recommended temperature and then take the difference between that and say 86F, which you might want to argue is a possibility for some folks who try keeping their reef tanks at 82 or 83F during hot weather, then the difference is only 0.5mg/l. If the difference of 0.3-0.5mg/l of oxygen in your tank makes a difference to your inhabitants, then you are seriously under-circulating and probably very overloaded to boot.

Oxygen saturation is a non-factor when comparing a reef tank at 77-80F and one at 80-83F. Proper water circulation is much more important.



Ref: From Dr. Rob Toonen's "Oxygen Saturation," November 1999.

[scottfaulkner11]

For those folks who have problems with temperature control, then they will have to do whatever is best to allow for their equipment limitations.

Right now my tank goes from 80- 83 exact, when its 110 outside thats the best i can keep it at. which so far, seems to do well for me. I also have a neighbor whose tank goes up to 85 and his sps seem to absolutely love it, he's run his tanks at that for several years and hasnt done any harm for him. As for the fall, winter, and spring i will most likely keep the temp a little bit lower. I cant do that in july or any other summer month though

[returnofsid]

Ninong, I'll end my part in this debate, by recommending you read Anthony Calfo's "Coral Propagation." If you have Volume 1, second edition, I'll direct you to page 115-117, where he talks, in great detail, about the reason HE recommends 76-80 and where HE goes into great detail debating the reasons NOT to keep reef systems above 82. Oh and he even uses the argument that some are making about warmer natural temps...and then goes on to point out the major bleaching events and heavy mortality that have recently taken place at many Pacific reef locals, especially the Caribbean reefs. He also goes on to talk about the problems associated with dissolved oxygen content, in a reef tank kept at higher temperatures...etc. I'd really recommend the reading. IMO, Anthony Calfo is one of the most respected and trustworthy "reef authors" out there. I'll follow "his" trends any day.

This being said, I do also understand the difficulties of keeping lower temperatures in the warmer climates, such as Texas and other Southern states.

[Ninong]

returnofsid,

I bought Anthony's book shortly after it came out. I'm glad that you enjoyed it. So did I.

Anthony prefers temps in the 76-80F range. You prefer temps in the 77-80F range. Delbeek & Sprung, in TRA-1, wrote that the ideal reef aquarium temperature is 74-76F.

I prefer temps in the 80-83F range, with 82F as my idea of an ideal reef temp. All of the polls that I have seen on the boards indicate that more people keep their reef aquariums above 80F than below; however, that's a matter of personal preference.

My argument in this thread is NOT with your choice of reef temperature. My argument in this thread is that AFTER someone asked if 80-83F would be a problem in his tank, I advised him that 80-83F would be fine as long as he didn't let it get above 84F; then you contradicted my advice with the already disproven claim that 77-80F is the universal choice for reef tanks. It may be your choice, it may be Calfo's choice and it may be the choice of a lot of hobbyists, but it is certainly NOT the universal choice. Your attempt to discredit my advice with that argument failed.

You then made the absurd claim that 77-80F is closer to natural reef temps. That claim displays a shocking lack of knowledge of reef ecology. I was obliged to correct that in this thread just for the record so that newcomers to the hobby wouldn't be misled.

You then made the factually incorrect claim that 80-83F is not safe because oxygen saturation is MUCH LOWER and would cause respiratory problems for the fish. It's not much lower than at 77-80F and it doesn't cause respiratory problems for the fish. In this regard I choose to accept the advice of Dr. Rob Toonen, who has not only been a reefkeeper since he was a young teenager, he is also the author of numerous peer-reviewed published articles in the scientific literature as well as countless articles published in hobby mags over the past 13 years. He currently runs The Toonen Lab for the Hawaii Institute of Marine Biology on Coconut Island where he is in charge of the sort of research that answers the questions the hobby authors speculate about. Some of Rob's research projects were designed specifically to answer questions for the reefkeeping hobby.

To quote Rob: "I am interested in aquarium science and the culture of marine ornamental species at a variety of levels. First of all, I have always been interested in the husbandry of marine ornamental species. But beyond that, I believe that it is both an important and rewarding pursuit to introduce primary research into the aquarium industry and vice-versa. Therefore, I write for a number of different hobby magazines on a regular basis, and I try to have at least one aquarium science research project underway in my lab at any given time."

[charlie]

Hey George, have you seen the June advanced aquarist?? Dana Riddle is recommending the top reef temp in home aquaria as 80 degrees. Just thought I would throw that in here

[Ninong]

Charlie,

That was an interesting article that Dana wrote. I wonder why he chose a Hawaiian reef as his only example to compare to his 140-gal aquarium?

Hawaiian reefs are 19 to 22 degrees northern latitude and have very limitied coral diversity compared to reefs that are closer to the equator. I don't think any of the Hawaiian reefs can be considered typical reefs. Not only is the temperature different but the salinity will be lower.

One would expect that he would have chosen as an example a reef on the northern GBR or maybe Indonesia or even the Philippines -- anyplace but Hawaii.



P.S. -- Dr. Randy Holmes-Farley has a nice article that compares natural seawater water parameters to what he considers an acceptable range for those same parameters in a reef aquarium. Check it out.

Note that for temperature Randy gives a range of between 76-83F. That's not to say that he thinks your aquarium's temperature should swing from 76-83F every day, he's just saying that in his opinion temperatures between 76 and 83 degrees Fahrenheit are acceptable. Randy is very specific about salinity. He recommends 35 ppt. Period.

Dr. Ron Shimek recommends 80-84F for temperature and 35 ppt for salinity. Dr. Craig Bingman keeps his reef aquarium between 80-82F. Dr. Rob Toonen used to recommend 82-84F but I'm not sure if that's still his recommendation because now that he's studying Hawaiian reefs for a living, maybe his current temperature recommendation is closer to Dana's?

It was in this Feb. 2, 2000 exchange between Craig and Rob where Craig told Rob that he maintains his tank between 80-82F and Rob told him that he believed 82-84F would be better. (P.S. -- Apparently 82-84F is still Rob's recommended temperature because he links to that Feb. 2, 2000 exchange on his lab's website.)

[Ninong]

Charlie,

I know you like Dr. Sanjay Joshi's articles, so I thought I would point out that he keeps his personal reef tanks at "79 to 82 degrees Fahrenheit in the winter and 81 to 84 degrees in summer." Sanjay has been keeping reef tanks since 1991.

[Ninong]

Charlie,

Here is a YouTube video clip of Wayne Shang's 300-gal reef aquarium. Wayne has been keeping reef tanks for more than 20 years. You have probably seen photos of this particular 300-gal tank in several of the reefkeeping hobby books over the years. Wayne kept the temperature in that tank between 80-82F in the summer but it was allowed to drop below 80F in the winter. The tank was in his garage and it's expensive to maintain heat in the winter, as well as keeping it cool in the summer. Wayne's advice is to not allow the water temperature to get above 83F.

Wayne now has a 718-gal reef aquarium in his garage and a 300-gal FOWLR tank in his living room. The video clip on YouTube that I linked is of his old 300-gal reef. I have the complete hour-long DVD of that tank that includes a mass spawning of his more than two dozen mature Tridacna clams. The spawning portion of the DVD lasts more than 20 minutes. That's really a sight to see.

I just wanted to throw this one in here as an example of a tank that spans the range of temperature recommendations. In the summertime it's kept at the temperature range that I prefer and in the winter it's kept at the temperature you prefer. Wayne lives in Fremont, CA (East Bay), so the winters are very short.

The End.



P.S. -- All of the corals from Wayne's old 300-gal reef were transferred to the new 718-gal tank. The new tank is made of 3/4" Starphire with the overflow at the end of the tank. The other end and both long sides are visible. The dimensions are 96"L x 48"W x 36"H.

[charlie]

I have that exact video you speak of and every once in a while, I plug it in just to see what a real 300 looks like again. The clam spawning is awesome!!!!!
Let me ask a question here. Is it possible that because of the fact that alot of the corals we are getting in our tanks now are possibly 5th generation or more frags, is it possible that these corals are acclimating themselves to whatever temp the previous owner had, and that is why the temp range is 76-83???
Could the same be said of salinity nowadays?

[Ninong]

Charlie,

In their natural environment, corals adapt to their conditions, including variations in temperature and salinity, as well as light and water turbulence. You might not even recognize the same species of Montipora capricornis at 50-ft depth as being the same as one found at 5-ft depth. At deeper depths it will spread out more to expose more of its surface to sunlight. Staghorn type corals will have stouter branches in more turbulent water than they will in less turbulent water. And on and on.

Corals that experience wide swings in temperature in their natural environment are adapted to withstand such swings. They are subject to bleaching when the temperature rises more than 1C (1.8F) for two months straight or more than 2C (3.6F) for four weeks straight above their average maximum. That means that you could have the same species of coral that is found in more than one area and its tolerance for high temperatures will be based on the temperature range where it is found.

In some areas that could mean that a temperature of 89F, or even 91F, can be tolerated for short periods of time but in other areas 87F could mean trouble. Obviously the corals in Indonesian waters are adapted to higher temperatures than the corals in Fijian waters but the Fijian waters experience wider seasonal swings in temperature. I have posted a chart of the past 10 years of Fijian water temps on this board several times. Their temps run from a low of around 76-77F in their winter season to a high of around 85-86F in their summer. The farther you get from the equater the larger will be your seasonal variations in water temperature. Salinity also falls off as you get farther and farther away from the equator.

The reason that Wayne Shang keeps his reef aquarium at 80-82F and cautions against letting the temperature rise above 83F is because our reef tanks are coral gardens with a wide variety of species from different parts of the world. Very, very few hobbyists keep true biotope tanks. You aren't going to find anything close to a typical reef aquarium if you go diving. Most reefs contain only a few species of corals in one particular area. Those species can be said to dominate that area. Over a wider area, you will find a much wider diversity of coral species, but in one small area, not so much.

The reason we acclimate corals when we introduce them to our aquariums is because we usually don't know for sure what their previous environment was like, especially if it was wild collected. It takes about three weeks for a typical coral to adapt to changing light conditions in its natural environment. That's how long it takes for the zooxanthellae to go through the various adaptive changes.

If you are dealing with coral frags from mother colonies that have been captive bred for generations, then you probably know the water temps that they were adapted to in their captive environment. You should take that into consideration.

As Wayne puts it, he doesn't know where everything came from and that's why he has chosen a moderate temperature range of 80-82F as his maximum.

I guess if you are getting something from a tank that was kept at 74-76F, then you might want to take a longer time to acclimate it to much higher temps. BTW, Julian Sprung no longer recommends 74-76F as the ideal reef aquarium temperature, as he did in TRA-1. In his more recent talks, he has suggested 76-80F.

One of the arguments that Ron Shimek always makes is that corals in a reef aquarium that is kept at 82-84F are better able to withstand a temperature spike to 88F for short periods of time than corals that are kept at 76-78F. That's because the important thing is that it is the difference between their accustomed average maximum temperature and the temperature spike that is important, not the temperature of the spike itself. There is a 10-degree difference from 78 to 88 but only a 4-degree difference from 84 to 88. That's true. Obviously that's just one argument in favor of Ron's opinion on higher water temps. I can give you lots of reasons why many reef hobbyists prefer temps slightly lower than the range Ron prefers, starting with Wayne Shang's.

Ron's argument against reef tank temps below 80F is because at temps of 79F and below, some corals have greatly reduced growth. We can actually measure this and it has been done. Corals grow best when they are in a healthy environment that suits them. The same can be said for reproduction. Corals spawn when the temperature is at its seasonal high. That's because reproduction takes a lot of energy and they have more energy to spare when the temps are higher. For reefs close to the equator, this usually means a water temp of ~86F.

There are arguments that can be made in favor of 78F and there are arguments that can be made in favor of 82F. I guess that's why Dr. Randy Holmes-Farley gives 76-83F as an acceptable range.



P.S. -- Charlie, the Fijian water temps chart can be found in this thread from three years ago. My position on reef aquarium temperature is best put forth in my post #7 in that thread.

Indonesian water temps are obviously higher than Fijian water temps. Nowhere on the planet are corals found in greater density or diversity than on Indonesian reefs.