max safe FOWLR temp?

[agreeive?fish]

as the title states what is the max safe temp for a fowlr tank it looks like the 100-110 daily temps are gonna continue for my area for a while considering we still have the "normal" time frame of 100+ temps to go yet

[shaginwagon13]

what kind of fish you have in the tank?

[dzhuo]

The so-called "max temp" is not set genetically for most reef animals. Generally speaking, the safe zone is a few degree above what the animals have acclimated to. Within this range, pretty much any fluctuations is not stress to them. Most people keep tanks within 78F and 84F. The following is not my work but a fellow researcher who specialize in thermal stress in marine fish and anemone:

I work on thermal stress in reef animals, no naturally threads on this subject aggravate me because there's so much misinformation in the hobby regarding temperature and it's constantly being repeated as if it were fact.

To answer the original question, I let my tank get up to 86 regularly. On rare occasions it might climb to 88. Last year during a power outage it went to 92 for a few hours without issue.

Now to address the misinformation about what is harmful and what isn't when it comes to temps-

What kinds of temps are reefs seeing in the wild? The worldwide, yearly average is about 82. The average wintertime low is 77 and the average summertime high is 86. The often repeated "ideal" temperature of 78 replicates the low end of wintertime temperatures. Also, it has been documented that the minute-to-minute fluctuations in temperature are regularly as much as half of the yearly range with the magnitude of fluctuation increasing with depth down to 90-120 ft. There is absolutely no evidence that these fluctuations are stressful to reef animals, nor would you expect them to be since they have experienced these fluctuations for their entire evolutionary histories. In fact, there's limited evidence suggesting that these types of fluctuations may be important for modulating the stress threshold.

So if 78 isn't ideal then what is? For the hard corals we have optima for, it's about 82-84. That's also roughly the average for the area of the Indo-Pacific that represents the center of coral reef biodiversity. That's probably pretty close to the ideal average temperature.

How high is it safe to go? It depends. The answer varies from tank to tank. The stress threshold is not set genetically. It changes depending on the ambient temperature regime. The simple answer is that you're safe to go 2 degrees above the normal maximum temp. That's why it really bugs me to see statements like "above X degrees is just asking for trouble." It all depends on what the temperature normally is.

Another statement that bugs me is "a colder temp offers a wider margin of error in case of an emergency." This assumes that 1) the stress threshold is a set number, which as I already pointed out isn't true, and 2) that the animals in a cooler tank will respire less if there's an emergency. There's not much data on the second assumption, but from the little we have that assumption doesn't seem to be true. At rest, under normal conditions, if you have one specimen (A) at 78 deg F and another (B) of the same species and the same size at 80 deg F, then B will have a higher respiration rate than A. However, as the temperature increases, the respiration rate of A quickly out-paces that of B and for any further non-lethal temperature, B will always be consuming less oxygen than A. In other words, at 80 degrees, A will use more O2 than B does at the same temp. The same is true for 82, 84, etc.

The difference in O2 saturation over the range of temps we keep in reefs is so small that it's essentially negligible. Even at 90, the saturation point is still double the safe lower limit. {For example, from a 76F to 82F end points, both still holds more than 200% more oxygen above the warning zone}

[JoeRonda]

^^^^That is very interesting reading^^^^^ Puts my mind at ease with a temp range of 79-83F

[dzhuo]

Originally Posted by JoeRonda

Puts my mind at ease with a temp range of 79-83F

79F and 83F is absolutely nothing to worry about. Most recent studies have shown in a typical reef, temp can swing 4 or 5 degrees hourly. It really bugs me that most people are worry about such fluctuations and would spend extra money and effort with chiller to control a few degree of swings to "help" the corals and fish not knowing this actually hurts them. The myth that these swings are stressful to reef animals originated from a few research papers done on fresh water (regarding ich) a long time ago which do not apply to reef animal. Even in a closed system (like our tank), there is no evident that temp swings within the safe zone which fish and corals acclimated to are stressful.

[agreeive?fish]

thanks the article was informative i am not near as worried about my 85 temp now. i still don't like it that high but since it climbed from my normal 79/80 as the summer ambient temps correspondingly above the air conditioners ability to keep my house below 80 i am not as worried

[sbshady]

My thermostat in my house stays at 75. Our main level is partially in a hill so it stays cool. my tank still hovers around 82-84. Dont feel so bad now. I was putting frozen saltwater in milk jugs in my sump and continually changing them out because I thought that temp was too high. Glad I read all of this. Can finally sit back and enjoy looking at the tank, lol.

[agreeive?fish]

Originally Posted by shaginwagon13

what kind of fish you have in the tank?

regal angel(grey belly) (reef tank)
scribbled angel
personifer angel
asfur angel

blonde naso tang
yellow tang (reef tank)
hippo tang
convict tang
sailfin tang
purple tang

porcupine puffer
stars/stripes puffer
green spotted puffers


harlequin tusk (aussie)
fox face
scat
green bird wrasse
blue hamlet

purple fire fish(reef tank)
royal gramma (reef tank)
purple queen anthisis (reef tank)
mollies(all salty tanks)
several types of damsels(all salty tanks)
3 types of clown fish

divided between 4 tanks, plus 3 freshwater tanks.. the reef tank is not running warm because its sump location is right in front of the ac vent(temp location due to wife's surgery and the need of temp use of a wheel chair)

[Orcrone]

I went scuba diving in Key Largo in February when the water temp was 72 & my girlfriend went back in August when the water temp was 86. They can handle a range of temps, they just don't like large sudden swings.

[RAJOD]

Adding to the confusion are stores like dr fosters which list temps of 72-78 for most of the fish. 80 and higher is never listed

[Reefmedic79]

Nothing like bringing back a post that is 2+ years old.

[RAJOD]

Originally Posted by Reefmedic79

Nothing like bringing back a post that is 2+ years old.

Old to you new to me.