Yikes 88 degrees!

[widmer]

Came home tonight and found the apartment a lot warmer than the A/C should have allowed it to be, the tank was 88 degrees. I freaked out, considering just this morning I bought the healthiest, best coloration coral beauty angel I've ever seen. Everyone seems to be OK including the coral beauty angel, the pepperment shrimp and the snails. I've got fans on it and the auxilliary A/C cranked up, I'm hoping to drop by a degree per hour. Anyone ever had their temps go this high?

[Peter Eichler]

Yes, and odds are many of your tanks inhabitants have experienced it in nature as well. I'd suggest not doing it over long periods of time, but it's not out of the natural ranges of most Indo Pacific reefs. A swing up to 88 is usually going to be toughest on people that maintain their tanks at unaturally low levels and maintain the exact same temperature over extended periods of time.

[widmer]

Thanks for the words of comfort. I'd really hate to lose this coral beauty, I can't describe how great it is as far as coloration and overall health. And for only $30. My temps have dropped down to ~85 over the past hour and a half, so I'll let them drop more gradually from here on out. It might be time to invest in a chiller.

[greenbean36191]

Sure, my tank used to hit 88 fairly often. It's not really a huge deal and like Peter said, it's not that unusual for many reefs. As long as it's just a short stint there and the temp isn't normally substantially colder than that I wouldn't expect to see any problems at all.

Once my tank even hit 92 during a power outage without any problems.

[stagefright13]

I've also gone up around there with no ill effects. Think it was almost 90. But It was my fault because I was doing some maintenance And accidentally bumped the heater control knob on the outlet. I keep everything at 80 all the time anyway. That way there aren't any swings. With hot days or the air conditioner.

[am3gross]

yeah i have had some hot days here to. i have actually noticed a little better growth out of some of my corals. i would not suggest keeping the temps high by any means but every once in awhile is not bad.

[snorvich]

Alternatively, use fans. They cause evaporation which causes a cooling effect. But that means you lose water which must be replenished. I keep my tanks at a lower temperature for various reasons but as Peter said, nature can provide surprises. Over longer periods of time, high temperatures can cause bleaching of corals.

[K' Family Reef]

when nutrients are high
then your corals will get stressed at higher temps but if they are kept in check then you shouldnt have a problem... fwiw there was even a member on here (JETCAT) a 30yr veteran reefer who said one of his tanks had been kept at over 90' for a summer yet still didnt show signs of stress bec the nutrients were kept low.

before purchased a po4 reactor
(po4 were little high) anytime the tank would hit 84/85 the corals would start showing signs of stress.

at that time i ran fans 24/7
to keep the temps down to 80-82

now the tank stays around 84/85
only run fans during the daytime and run them on low (saves a ton of electricity over last summer - not even running as many fans!)... corals appear atleast to be thriving iow dont see any signs of stress... yesterday the fans didnt come on (was working on back of tank and forgot to plug them back in) and didnt notice it until last p.m when i looked at the temp gauge... the temps were sitting right at 88-90'... corals all looked fine.

good luck.

regards

[greenbean36191]

There's a whole lot more to it than nutrients and I'm not sure there's really any connection there other than nutrients acting as a pre-existing stressor.

Generally, temperature associated bleaching is attributed to oxidative stress. What happens is that during the day the zooxanthellae are producing oxygen via photosynthesis. A lot of that is in the form of molecular oxygen, but a small part of it is what are known as reactive oxygen species. These ROS attack lipids, proteins, and DNA causing general cell damage. Eventually there is irreversible damage to the photosynthetic machinery in the zooxanthellae and the coral expels them.

Under normal conditions these ROS are in such low concentrations that any damage they cause is quickly repaired by the cells. Light levels, temperature, and water flow all play important roles in regulating the concentrations of the ROS though because the first two modulate how much photosynthesis is occurring (and the rate of ROS production) and water flow regulates how fast ROS can diffuse out of the cell. Under moderate to high lighting and warmer than normal temperatures, ROS start to accumulate in the tissue faster than they can diffuse out. They start attacking the cells and causing more damage than can be repaired. Increased water flow can help speed up diffusion and delay the onset of this accumulation. Similarly, decreased lighting can reduce or stop the production of new ROS.

In theory nutrients could increase zoox density and result in a higher rate of photosynthesis, but to my knowledge, neither zoox density or slightly elevated nutrient concentrations have ever been linked to increased bleaching susceptibility.

When it comes to temperature though, it still gets more complicated. There is no set temperature where stress starts to occur. It's a product of long-term acclimatization. Corals kept at cooler temperatures will show stress at lower temperatures than corals normally exposed to higher temperatures. Generally the rule is that stress begins with prolonged exposure to 2-4 degrees above the normal seasonal maximum. The average temperature doesn't really matter. That means that the same corals could bleach at 84 in March but be perfectly fine at 88 in July. You also see modulation of metabolic rates with acclimatization rather than just the normal increase with temps you might expect. This is mainly due to regulation of cellular repair mechanisms and using different forms of proteins that are stable at different temperatures. Taken together this means that keeping a tank cooler doesn't offer any more protection against dangerously high temperatures and respiration isn't significantly higher at a given temp for animals kept at warmer temperatures and may in fact be lower.

Basically, corals in general have a wide range of acceptable temperatures. The subset of those temperatures that are acceptable to certain corals will depend largely on the thermal history as well as several current environmental conditions, one of which may or may not be nutrients.

[K' Family Reef]

Originally posted by greenbean36191
There's a whole lot more to it than nutrients and I'm not sure there's really any connection there other than nutrients acting as a pre-existing stressor.

Generally, temperature associated bleaching is attributed to oxidative stress. What happens is that during the day the zooxanthellae are producing oxygen via photosynthesis. A lot of that is in the form of molecular oxygen, but a small part of it is what are known as reactive oxygen species. These ROS attack lipids, proteins, and DNA causing general cell damage. Eventually there is irreversible damage to the photosynthetic machinery in the zooxanthellae and the coral expels them.

Under normal conditions these ROS are in such low concentrations that any damage they cause is quickly repaired by the cells. Light levels, temperature, and water flow all play important roles in regulating the concentrations of the ROS though because the first two modulate how much photosynthesis is occurring (and the rate of ROS production) and water flow regulates how fast ROS can diffuse out of the cell. Under moderate to high lighting and warmer than normal temperatures, ROS start to accumulate in the tissue faster than they can diffuse out. They start attacking the cells and causing more damage than can be repaired. Increased water flow can help speed up diffusion and delay the onset of this accumulation. Similarly, decreased lighting can reduce or stop the production of new ROS.

In theory nutrients could increase zoox density and result in a higher rate of photosynthesis, but to my knowledge, neither zoox density or slightly elevated nutrient concentrations have ever been linked to increased bleaching susceptibility.

When it comes to temperature though, it still gets more complicated. There is no set temperature where stress starts to occur. It's a product of long-term acclimatization. Corals kept at cooler temperatures will show stress at lower temperatures than corals normally exposed to higher temperatures. Generally the rule is that stress begins with prolonged exposure to 2-4 degrees above the normal seasonal maximum. The average temperature doesn't really matter. That means that the same corals could bleach at 84 in March but be perfectly fine at 88 in July. You also see modulation of metabolic rates with acclimatization rather than just the normal increase with temps you might expect. This is mainly due to regulation of cellular repair mechanisms and using different forms of proteins that are stable at different temperatures.

Basically, corals in general have a wide range of acceptable temperatures. The subset of those temperatures that are acceptable to certain corals will depend largely on the thermal history as well as several current environmental conditions, one of which may or may not be nutrients.

interesting and informative article!

was just speaking from experience
it was a night/day difference after we added the po4 reactor... once the phosph levels were brought down (prob w/n a week) - the corals no longer showed any signs of stress (when temps climbed)... that was evidence enough that nutrients affected corals ability to handle the higher temps... few weeks ago noticed some of the corals showing stress for some reason... when did water tests the po4 was high (temps at around 85daily) - checked the reactor and there was no water flowing thru it (rio50motor was stopped up)... who knows how long it had been that way... corals have been fine since...

sure from a 'technical' perspective
there is more to the story... but from a real world reeftank perspective there seems to be atleast a correlation betw nutrients/temps and coral stress.

regards

[greenbean36191]

This is what I work on, so your story has me very interested, but I'm not sold yet on the idea that nutrients sensitized your corals to temp. My experience doesn't match yours, but this is a very complicated, hard to test question so it's hard to rule anything out.

Can you give me an idea of what the temp had been like shortly before and after you added the reactor? Had there been any recent changes in the temps? Had there been any spikes or abnormal temp swings within the past month or so or had the tank gradually been getting warmer recently? What signs of stress were you seeing?

[JJ21]

my tank got up about that high once. I lost a nice sized platygyra, a frag of leptastrea that was doing really well, an expensive frag of acan lords, and just about lost another frag of lords, but fortunately a polyp or two managed to hold on and it's making a comeback.

[Mykel Obvious]

JJ,
Sorry to hear about your loss!!

What is your normal tank temp and what kind of daily temp swing do you see? I'm running my tank with a daily swing from 81F to 84F with an occasional spike to 85F and occasional low of 80F... just curious how large the spike was on your tank that devastated your corals

[TellyFish]

get a reefkeeper jr... my tank has not fluctuated a single point between 79.6 and 89.4 in the past 3 months! The 1 degree fluctuation per day is programmed. I run the heater and two fans set up in 2 separate stages.

Works amazingly!!!

[Mykel Obvious]

Hmmm... maybe I should have stated that I run it that way on purpose?

Now I just need to figure out a way to automate seasonal variance for summer and winter