Acceptable Daily Temperature Range?

[ScubaFish802]

Hello, I have been working to keep my tanks temperature from varying so much throughout the day but have not been having much luck keeping it 100% stable. My question is what is the acceptable range for temperature / is it possible to keep the temperature actually level in an aquarium? - I'm just working to make things as stable as possible throughout the system.

Right now I have 1 heater in my sump, and 1 heater in my overflow (fully submerged). 1x 150w and 1x 250w - tank is 54 gal / sump 10 gal. Possibly they are just mis-sized on my part?

Here is what an average day looks like (the previous graph area where the plateau is I had accidentally pulled the probe out of position, so please ignore).

 

[Zach B]

I think this is acceptable. I try to keep my temperature within .6 degree swings but many allow their systems to fluctuate a bit more. Best of luck

 

[Cthulukelele]

Mine is typical within a degree, but there are hugely successful systems with daily temp swings of 2-3+ degrees and seasonal even larger

 

[ISpeakForTheSeas]

From everything I've seen, that fluctuation is totally fine:

Slightly diurnally and seasonally, yes:
"The diurnal temperature variations are about 0.3°C in theopen oceans and 2 to 3°C in shallow waters."
Source: https://www.academia.edu/36838790/Chemical_Oceanography
From what I've seen, for most tropical reef organisms, as long as the temp doesn't swing too far too fast, and as long as the temp is kept within ~75-82F (lower than 74ish can start causing problems, higher than 83 and many corals will start to bleach - so allowing for temp variation due to imperfect temp controllers in our tanks, I would set 75F as the min and 82F as the max), the temp doesn't seem to matter much. To give an idea, a 2C change (from 25C to 27C, for example) is about a 3.5F change (77 to 80.6, with the 25C to 27C example), so allowing a 3F to 4F temp change diurnally should be fine.

Some info on coral and temperature:

I’ve been reading through a bit of literature on corals and temperatures, and - generally speaking - 83F is considered the safe limit you don’t want to go beyond, so some people might recommend not going above 82 as a precaution.
Edit: when accounting for the slight inaccuracies of our heaters/controllers, I personally would set 82F as the limit.

That said, though, there are a number of caveats that determine what temperature is too high. To list a few:
1) the location the coral was collected from (some coral reefs have higher temperature tolerances based on their geography than others - 83F [technically like 83.6F or so] is the limit for the least heat resistant reefs, if I recall correctly; I believe somewhere around 87-89F was the limit for the most heat resistant).
2 ) temperature stability (the more stable the temperature the coral is used to, the less it’ll like changes to temperature).
3) how long the coral has to acclimate to the higher temperature (slow and steady wins the race).
4) corals can handle temperatures above their temperature limit for a limited amount of time (if the temperature is only slightly over, the corals only start showing distress/begin bleaching after a few days [four days at 1-2F over, if I recall correctly]; if the temperature is significantly above the limit, the corals will show distress/bleaching within hours).

So, as Tamberav and a few others I’ve seen here on the forums can attest, 86 may not be too hot, but - personally- if you’re going to run a tank that hot I’d take things nice and slow (likely ramping up over the course of a month or two) to get the corals there as a precaution.

 

[Lbrdsoxfan]

Everything sees more than that in the wild, It's fine.

 

[KStatefan]

Less wattage would flaten the slope of the heat curve some.Would not change the range but there would be fewer cycles.

 

[vetteguy53081]

Hello, I have been working to keep my tanks temperature from varying so much throughout the day but have not been having much luck keeping it 100% stable. My question is what is the acceptable range for temperature / is it possible to keep the temperature actually level in an aquarium? - I'm just working to make things as stable as possible throughout the system.

Right now I have 1 heater in my sump, and 1 heater in my overflow (fully submerged). 1x 150w and 1x 250w - tank is 54 gal / sump 10 gal. Possibly they are just mis-sized on my part?

Here is what an average day looks like (the previous graph area where the plateau is I had accidentally pulled the probe out of position, so please ignore).

This will be a variable question as many will have various ranges they use and prefer based on Fish only-mixed reef- shark specific which is cooler and other species which come from cooler regions (island and tropical waters.)
Best to follow the rule of ocean values which is 76-80 degrees. I keep mine which is mixed reef at 78 often at _/- .5