Low temps vs high(er)

[Dan H]

So back when Meg and I first got in to the hobby, the rule of thumb was to avoid higher temps or risk bleaching or death of your corals - in fact, everyone seems to shoot for 79 degrees. The battle was always keeping the temp down, mostly because we had lots of halides and an enclosed canopy. So we ended up having large fans to increase evaporation and keep the temps down. The result was evaporating about 5 gallons / day on a 200 gallon system! But, we kept the temps below 82ish at all costs. In fact, we got scared when we approached 82.

So because the nerd in me wants to aim for a number - this time around when researching what is the optimal temp, I ran across an interesting article by Ron Shimek whom I'm sure you all know: http://www.ronshimek.com/salinity_temperature.html

If you don't have time to read it (you should as it's really interesting) the basic summary is that we're keeping our tanks too cold! 79 too cold? He's suggesting at 79 and below, the metabolic rates of the animals slow to a point of potential starvation. In fact, he suggests we should never go below 80.6 and probably target in the 80-84 range. Wow. Anecdotally, that may help explain some of our accidental success back then as our tank was usually running "hot" in the 81-82 range.

So, what temp is your system shooting for? I think I'm going to target 82 +/- 1 degree.

[+brian.srock]

I have been keeping my tank at 81-82. I check out all the tank of the month stats on reefkeeping.com and have asked others that have tanks I want to mimic and I find most are running 82.

I've also found they keep salinity at 1.026, Ca 420, Alk 8dKH, Mag, 1350.

You'll probably get all types of answers regarding parameters so I would check out the tanks you want to create and mimic that way.

[madsalt]

That is interesting as I actually keep my tank at 77. This may be something I need to dig into deeper to see if I should consider slowly moving my temp up.

[victoly]

I think its important to consider that natural conditions (i.e., NSW) don't always have the highest "success", as we define success in the hobby on a personal level. To take this to a totally far-flung conclusion, If we used natural conditions for farming, we would all starve. Temp, salinity, alk and phosphate are parameters where, again IMO, stability trumps shooting for a discrete value. I feel about temperature like I feel about alk, that is to say that there is a range of values which people have had success with. I try to stay in the middle of that range when it is reasonable to do so. That way if when I have an equipment failure, I have a safety margin. Additionally, I think it's worth it to try to reduce risk by not having critical equipment cycling constantly. For example, if my house naturally keeps my tank at 78 degrees, is it really worth the a) cost of electricity and b) risk that cycling my heater 20x throughout the course of the day, *every* day will lead to a stock killing failure? Probably not.

[Neon Reefer]

Yes I have read the article and although his facts are straight, it doesn't mean this is the only path to success. More like running Windows on your desk top: IE there are many ways to accomplish the same task and all are correct. I poo poo'd some of "the metabolic rates of the animals slow to a point of potential starvation" simply because of accounting for deep-water species that naturally live comfortably in temps below the 78F mark. IME even shallow water species can easily be adapted to colder temps than the 80.6F mark.

In addition many of us are not just "coral guys" but also enjoy marine species outside of inverts. I know my fish became somewhat agitated at 82F. Back when I was running CF bulbs, a closed tank, and a chiller just to maintain an < 82F temp on those hot 100+F summer days when it was impractical to keep my house under 78F. I saw as the temperature rose the fish become more agitated.

I believe that most, not all coral will over time acclimate to the temps we keep in our tanks over a broader range of 77 - 82 F. The main thing being consistent temperatures. My current set up runs ~ 5 degrees warmer than ambient room temperature and I like my tank to stay @ 80F all the time. So during winter months the heater runs in the tank and in the summer months the AC runs in the house to maintain 75F ambient temps and the aquarium heater gets a needed rest. But my coral and fish stay nice and cozy year round. Same as the lighting too. I never dial back the intensity and duration of my lights to simulate winter months. Do you? I like year round summer in my tank and this makes up the small difference in potential growth rates between the 80.6F suggested temps and the year round 80F temps I keep. But the article did provide me with some ease of mind knowing my coral won't melt away at 82F.

[mFrame]

I also believe that at higher temps many pests proliferate faster due to their metabolism running faster. It's actually a prescribed method of ridding your tank of ich by starting a treatment and raising temperature to hasten the life cycle.

I don't believe a change of a few degrees will significantly lengthen or shorten our livestock's lives, but I do believe that significantly higher or lower temperatures put you closer to the terminal line should something else go wrong in the tank. I'd love to know what the mean desirable temperature is and target that rather than a point at either end of the curve.

[jestep]

I was running stable temp around 81 and I had way more problems bleaching. May not be the temp itself, but the proximity to the high temp seems to exaggerate the negative effect of other parameter changes.

[Timfish]

Shimek does present a good argument and from what I've read many corals don't start having issues with heat until temps go above 86F. But Shimek also gives the link to Kleypas, et all, (1999) that show in nature there is a huge variabiity of parameters on different reefs. And there is plenty of research showing corals "learn" and remember their environemnt (See link in my thread on decadal memory in the "Marine News" forum) so besides the above points we may also need to ask what parameters has your coral learned to prefer? My own experience is variation in temps don't matter that much. This system I maintained saw seasonal fluctuations of 12 to 14 degrees fareneight and the only problem I notice is the birdsnest would partially bleach when temps dropped below 72 degrees farenhight:

Here's a link to Kleypas's research: http://www.denix.osd.mil/nr/crid/Coral_Reef_Iniative_Database/Human_Effects_files/Kleypas%20et%20al.,%201999.pdf

[FarmerTy]

+1 to what everyone has said so far. I personally run mine at an average of 81-82 degrees but I let the season dictate the temperature average for my tank as I try not to fight the heating/cooling desires of 250 gallons too much.