Daily temp swing

M

MG98

New member
So I've got my main 120g tank set up with all equipment running except the heater. I've been keeping an eye on the daily temp range with my apex and it looks like I'm staying between 75.8-76.8 throughout the day.

The a/c keeps the house at 76 during the middle of the day and about 74 at night. I'm looking to set the temp on the apex/heater at the sweet spot where the a/c and water volume do the heavy lifting to maintain temp rather than the heater since the a/c is more reliable and I'll notice right away if it ever goes out.

Temp. stability being an important parameter I'm curious what the consensus is as far as "stable" temperature. I don't want to set too narrow a range that my apex is constantly turning the heater on/off.

What do you guys think?
 
Excellent question that I don't know the answer to unfortunately. My temp varies usually 2 degrees in a day (78-80), so I'm curious what "stable" is... Looking forward to what the pros here have to say :)

Sent from my SM-G955U using Tapatalk
 
FWIW one of my older tanks used to swing about 5 or 6 degrees on a daily basis in the summer and I never had any problems. (mixed reef) I'm not sure if you've ever been to the tropics before, but that water can go from warm to cold in the blink of an eye. I'm pretty sure that the corals we keep were designed for these types of changes. Some of them are left high & dry during low tide.
 
My temp swing and a/c 76 day and 74 night. Three 250 watt MH send it up during the day
 

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When I first setup my 120 I was looking for the same question.

What I finally found was the recommendation is the temp can be anywhere from 77 to 82 degrees, but the recommendation is to try and not let the tank swing more than 3 degrees in one 24 hour period.

I have my heater set to turn on at 77 and off at 78. My Chiller comes on at 80 and goes off at 79.

My tank has only once swung from 77 to 80 in one day.
 
I have an inkbird connected to a fan on top of one of my tanks and my temp stays between 75 and 76 degrees F. The other tank swings between 76 and 78 degrees F. I decided to order another inkbird for my second tank because I like stable temps, but I think a 3-4 degree swing across a long period of time is not going to do any damage except to the most sensitive specimens.
 
Mine is 78.8 during the night and day during the winter. In summer it swings between 78.8 and 82.4. For several days it can go as high as 87. Never had an issue
 
i keep my tank heaters set at 75 but the temps will sometimes in the spring and fall drop to 72 .. and as high as 77 in the mid summer...

Long ago it was suggested to get temps at 72 deg in reef tanks...
 
I used to think a 2 to 3 degree swing a day was fine as it didn't look like it affected my corals, however with my new tank Ive changed my mind. My controller came with a salinity monitor and as my temp changed so did my salinity.

Forgot by how much, but it was a considerable amount (I'm sure there's a chart somewhere online).

If your keeping corals, I would try to keep it as stable as possible. I believe that coral growth is negatively affected by a 2 to 3 degree swing.

I have a .5 degree swing.
 
activecactus said:
I used to think a 2 to 3 degree swing a day was fine as it didn't look like it affected my corals, however with my new tank Ive changed my mind. My controller came with a salinity monitor and as my temp changed so did my salinity.

Forgot by how much, but it was a considerable amount (I'm sure there's a chart somewhere online).
Click to expand...

So this post peaked my curiosity and I did some googling for salinity/temp conversions and stumbled across this article

http://web.archive.org/web/20001119...om/fish2/aqfm/1997/nov/features/1/default.asp

The gist is that avg reef temps are 82-84 and most hobbyists are keeping temps at the very low end of the acceptable limit. There's a neat link to monthly avg surface temps in the article as well.

Anyways after reading this I'm convinced that the stability range is only really important at the fringes of acceptable temp limits and a daily swing of several degrees is no big deal if the avg is close to the 82-84 range.
 
MG98 said:
So this post peaked my curiosity and I did some googling for salinity/temp conversions and stumbled across this article

http://web.archive.org/web/20001119...om/fish2/aqfm/1997/nov/features/1/default.asp

The gist is that avg reef temps are 82-84 and most hobbyists are keeping temps at the very low end of the acceptable limit. There's a neat link to monthly avg surface temps in the article as well.

Anyways after reading this I'm convinced that the stability range is only really important at the fringes of acceptable temp limits and a daily swing of several degrees is no big deal if the avg is close to the 82-84 range.
Click to expand...

Good article
According to that article(for me) 3degree change in temp is .6ppt change in salinity.
I keep my temp at the lower end. 78-79 degrees.
I might raise my temp after reading that.
 
Last edited:
Since Ive added my apex Iv been able to reduce my temp swing to 0.xx my a/c is set to 78 all the time the heater in my sump is set to 80 my apex is set for 77.1 to 78.9, Ive been watching from work and the temp has stayed pretty close to the 78 mark only dropping below that in the early morning hours.
 
My tank will hit 76 on some of the coldest days in winter where I'm at, but the oversized heater I have won't let it fall below that. I don't really worry about temperature too much though. As long as it hovers somewhere between 76-84 throughout the year everything seems to be fine.
 
activecactus said:
I used to think a 2 to 3 degree swing a day was fine as it didn't look like it affected my corals, however with my new tank Ive changed my mind. My controller came with a salinity monitor and as my temp changed so did my salinity.

Forgot by how much, but it was a considerable amount (I'm sure there's a chart somewhere online).

If your keeping corals, I would try to keep it as stable as possible. I believe that coral growth is negatively affected by a 2 to 3 degree swing.

I have a .5 degree swing.
Click to expand...

Here is a chart and I see no correlation
 

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You could be right. Just not as strong as the relationship between ORP andPH.

Also the Apex basically measures PPT SG might be more stable. Part of chemistry I do not understand.
 
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