Temperature Question

[oh207]

Hey MR, I've been pondering this issue for the past few weeks and would like to know how others have their fans or chillers set to cool their tanks.

How much do you allow the temperature to sway in your reef aquarium? I have a fan over my DT and another over my Sump.
The fan over the DT comes on at 80.5 and turns off at 79.8. The fan over the sump comes on at 80.7 and cuts off at 79.8 (essentially if its a hot day and the DT fan is not able to stop the rise in temp).
This has been working well for me. But I'm wondering if this is an ideal setting. Should the ON/OFF range be longer or shorter? What are the effects of waiting for the temperature to rise .7 degrees and having the fan work to cool it down, rather than having a range of lets say .2?
In which case will the fan work longer? And which case will result in more water evaporation. I don't really care too much about electricity consumption. Evaporation is my primary concern because i'm already refilling the ATO twice a week.

Here is a Fusion graph of temp swings. Should I try to have it settle out to a straighter line?

 

[bkstang]

I don't think your temperature swing is large. What I learned 1 degree within 24 hour period is quite fine. My temperature swing is a little bit higher during summer months, about 1.5 degrees. Fan turns on at 81.8 and turns off at 80.9. I don't see any ill effects on my livestock. What I did also, I created a virtual outlet that turns the fan on every hour from 11 am to 6 pm if the temperature is above 80.3. The fan runs for 10 minutes if it doesn't reach the minimum temp setting (80.9). So this additionally stabilizes the temperature. Here is my graph but the virtual outlet was turned off the last several days because the temp in NY was a little bit lower.

 

[lnevo]

A lot of heaters have a 2 degree variance built in. I wouldn't worry as long as your within range of a degree or two, I would think it normal and I doubt the ocean stays the exact temperature all day as currents from north and south move back and forth bringing colder or warmer temps. I could be wrong though...

 

[Reef Lobster]

lowering the range to a lower degree with cause the fan to be on much more (possibly 24.7) that would cause mroe evaporation and more electricity cost.


So if the only issue here is evaporation for you heres my solution:

Have either glass covers on both the sump and the DT or just the sump

I know everyone goes open top for better light penetration so if thats a concern lets take a look at my 2nd step of my solution

2)

switch which fan goes on first. Have the sump fan be the main and DT fan as backup. Throw the cover over the sump to stop the evaporation. This will cause the water to colelct and drip back down. So if in your fuge light PAR isnt a concern then do exactly that.

In fact, its what I do and I had a similar setup to you which is why im speaking from experience when i say your top off will reduce.