[tech1]

howdy all. My 85 hex, which I've had for 7 years, split down the side and was shooting out water around 5 am a few weeks ago. I've got a new tank built by Gene from undersea Odyssey (anyone in alexandria, louisiana); and he built a closed loop system for flow in it. It is a 62 gallon rectangle, problem is the Gen X pump for the closed loop and my other pump for the sump is causing the temp to stay around 81-82 degrees. I unplugged the heater. Anyone have a suggestion to knocking it down a few degrees.

thanks

[Big B]

Running a fan across the top of the tank is usually good for a couple degrees.

[greenbean36191]

81-82 is pretty much ideal anyway.

[Reefland]

I agree, and don't see a problem with that temp. However as suggested, a fan blowing across the surface will help a little.

[tullsterx]

Also, put the heaters back. It's more important that the temp stay as consistent as possible. Set the heaters so that they can help keep the temp consistently near your natural high temp. I just learned this recently around here and it makes a lot of sense. If you're high during the day is say 81. You don't want to remove the heaters and then have the temp drop to 75 every night. Better to keep the heaters so that the temp stays near 81.

[greenbean36191]

Consistency is completely unnatural and isn't important at all. It does more harm than good. There is no reason to believe that it reduces stress, and in fact it's known that it reduces the ability of the animals to deal with elevated temperatures or natural variation in the future.

[tullsterx]

Originally Posted by greenbean36191

Consistency is completely unnatural and isn't important at all. It does more harm than good. There is no reason to believe that it reduces stress, and in fact it's known that it reduces the ability of the animals to deal with elevated temperatures or natural variation in the future.

Sorry but that's completely wrong and makes no sense whatsoever. Why do you think we take such care in acclimating creatures to the temp of our aquarium water in the first place. To avoid the stress due to rapid temperature changes. You think a couple of 100 gallons of water can maintain it's temp as naturally consistently as all of the water in the oceans?

[greenbean36191]

Absolutely we can keep 100 gal of water as stable as the ocean. Most people keep it much MORE stable. Acclimation is for parameters like pH and salinity, not temperature. The temps over the reef AREN'T consistent at all. The average daily range near the surface is ~4-6F and can occur in less than 1 minute. Variation only increases with depth and can be ~10 degrees per minute between 60 and 90 ft. There are numerous papers to that end and anyone that has spent a fair amount of time diving on the reefs can attest to it. That's the kind of environment reef animals evolved in an there is absolutely no reason to believe that they're stressful. In fact Brian Helmuth and others have even written about how the fluctuations are important for maintaining the reef. The idea that fluctuating temperatures are dangerous or stressful doesn't exist outside of the hobby.

[tullsterx]

Maintaining temperature stability is over half the point of having heaters in the first place. Also, temperature is an important aspect of acclimaton. I guess what you're saying just flies in the face of everything I've read over the last 15 years regarding maintaining marine aquariums. Plus, I think there's a difference between the fluctuating temperature of different currents that's largely based upon vertical water movement across the reef, and the overall temp changes throughout the day. Ocean temps don't drop radically at night. And without heaters that can be a threat if you decide to turn your home heat down during sleep, etc. Maintaining a tight daily temperature range makes all of the sense in the world.

So, you really think that it wouldn't matter if the temp in a reef tank dropped to 60 degrees every night and then came back up to 81 every day? You're saying that the range of daily temperature fluctuations doesn't matter at all?

[leebca]

According to the veterinarians and professional aquarists, a drop in temperature of as little as 2F reduces a fish's ability to resist parasites and infection. A reduction in temperature reduces the full benefits of the mucous coating. A rise in temperature, however, has not been shown to have as much an effect.

In the '70's I've verified part of this, taking Marine Ich resistant fishes and dropping the temperature 10F in 12 hours. The control group went on as 'usual.' The fishes in the lowered temperature group broke out with a bloom of Marine Ich and 40% died.

When a temperature drops in a captive environment it is possible to see Marine Ich (if present) and other pathogens get an upper hand on marine fishes. I can't speak for other marine life forms.

If the marine system is pathogen free, and the system managed to reduce/control the numbers of bacteria, I know there will be no noticeable effect on captive marine fishes from a temperature drop. I have (not on purpose) dropped the temperature of pathogen-free marine systems by up to 8F in 6 hours without any noticeable negative effect on the fishes.

It is still a good recommendation in my opinion to control temperature within a narrow band or near +-2F shift when the captive environment is known to contain pathogens, or pathogen presence is unknown, for marine fishes.

[Samper]

Would anyone agree that it would be better if we could maintain +- 2 degrees from 76 instead of the standard 80-82?
Gavin over at Pacific Aqua Farms quoted me the temperatures from some of their stations the other day and the majority of them were around 65 degrees. Their divers had to wear 3mm wetsuits to get the acros. He went on and on about lower temperatures in aquaria helping with algae control and so on and how certain hobby authors had no clue what they were talking about just because they wade into a lagoon during low tide and drop in a thermometer. He said he maintains 76 degrees in his own tanks.

[leebca]

IMO temperature setting is a bit over emphasized. The correct/optimum temperature is the temperature the marine life forms are used to living in. When marine systems are setup they end up containing a wide range of life from different areas. In such a mix it isn't possible to give each its proper temperature.

I keep my FOWLR system at 76F +-1F using a heavy duty chiller. The purpose of this is to keep their metabolism lower, reduce evaporation, and to better manage nitrogen wastes. Although a lower temperature does increase the amount of dissolved gases, it isn't a significant factor. What is most significant is to provide an environment suitable to the life.

You might this perspective an interesting read:
What are Natural Reef Salinities and Temperatures. . .

[greenbean36191]

lus, I think there's a difference between the fluctuating temperature of different currents that's largely based upon vertical water movement across the reef, and the overall temp changes throughout the day. Ocean temps don't drop radically at night.

And what would that difference be? The changes from internal tides and waves are felt all the way to the surface and last in length for up to 4 hours at a time, twice a day. Diurnal variation can be strong in the first 10 m, especially on the back reef, lagoon, and reef crest. Tidal variation can also be strong in the same areas.

So, you really think that it wouldn't matter if the temp in a reef tank dropped to 60 degrees every night and then came back up to 81 every day? You're saying that the range of daily temperature fluctuations doesn't matter at all?

I never said that at all. I would never let a tank fluctuate that much or get nearly that low. I have absolutely no qualms about letting a tank experience fluctuations on the order of magnitude typically seen in nature though (~4-6 F). Many researchers have written on the importance of these fluctuations for the hardiness of corals and the health of the reef overall and IME they're spot on. My experience is completely in line with their writing.

According to the veterinarians and professional aquarists, a drop in temperature of as little as 2F reduces a fish's ability to resist parasites and infection. A reduction in temperature reduces the full benefits of the mucous coating. A rise in temperature, however, has not been shown to have as much an effect.

In the '70's I've verified part of this, taking Marine Ich resistant fishes and dropping the temperature 10F in 12 hours. The control group went on as 'usual.' The fishes in the lowered temperature group broke out with a bloom of Marine Ich and 40% died.

The only published reports I've ever been able to find to this end are regarding freshwater fish that don't normally see the magnitude of fluctuations seen daily by fish on the reef. Without comparable data for reef fish, I don't see any reason to believe the results are relevant. I certainly don't doubt the results you got, but I need more context. What fish were you using and what kind of conditions were they kept in before the experiment? You always have to keep acclimatization in mind with these animals. People have shown with corals that depending on their treatment prior to experimentation, mimicing natural fluctuations and high temps can cause either no effect or extreme stress and even bleaching (which is a large reason why fluctuations are important). You would expect to see the same results with any ectotherm including fish. I've certainly never seen or read about a disease gradient that increases with depth (and temp variablility) and the majority of fish don't migrate across the reef along temp isoclines.

[leebca]

My comments, experiments and experience is based upon captive marine ornamental fishes. The works of veterinarian colleges is on aquacultured food fishes.

Although our work can be duplicated in captive marine life, and you're welcome to perform such experiments, it has to be kept in mind that comparing the wild environment to the captive environment just doesn't work in many if not most of the issues. Captive fish are faced with an environment not duplicated in the wild. The temperature effects on disease and illness in the captive environment is studied well enough, I don't know of any parallel studies in the wild, however the environments are sufficiently different and it is how well the fish is equipped to handle its environment in the captive life that is my primary expertise.

[greenbean36191]

IMO it seems like a bit of a cop-out to say that our tanks and the wild are different without offering an explanation of what those differences are and how you expect them to affect the animals. There's nothing inherent about captivity itself that I can think of that would change the physiological tolerance of our animals to thermal stress. IME there isn't and others have done work that seems to confirm that. There are lab experiments done with wild and captive grown corals that show that if they come from cool, stable conditions (wild or captive), they don't tolerate higher or fluctuating conditions. That doesn't mean that fluctuations are unhealthy for corals, in fact corals that normally experienced them didn't show any signs of stress due to fluctuations or elevated temps into the high 80s. All it means is that the history of the animals can introduce artifacts into your test. You would expect the same to be true for fish, which is why how the fish were kept before the test is an important question. Like I said, I don't doubt your results, but all I know about your experiment is from the 2 or 3 sentence blurb and from that it's hard for me to buy into a more general statement about the role of fluctuations in fish health.

[leebca]

I appreciate your skepticism.