14g BC Temp Problems

[liverock27]

I have 14gal Biocube that I setup the other day and I am having trouble keeping the temp. up during the night. I have a 50w finnex titanium heater in the 1st chamber in the back and it is set for 79degrees. During the day with the lights on (3x24w pcs) the temp stays at a constant 78.6 degrees. Even when only the actinic bulb is on in the evening it stays this temp. During the night when no lights are on is when I have the problem. The temp has dropped to 76.8 degrees both nights. The only thing I can think to do is put the fans on a timer to run only w/the lights on. I turned off the fans this morning to see if the temp will rise before 11am when the actinics come on. I thought about keeping the tank at a lower temp., but I still think I would have the same temp loss during the night. Any suggestions would be great. Thanks for any help yall can provide. Other than this the tank looks great and I am enjoying being back in the hobby.

 

[gmann1139]

You might actually have a different, slighter easier problem: Your heater's thermometer isn't accurate. I know I have one that I have to keep set several degrees higher in order to keep my tank at the 'right' temperature. Try setting yours 2 degrees higher, and see if that solves the problem.
If not, you do need to have the fans running only when the lights are on. Here's why:
During the day, the heater never turns on, because its always in a 'hot enough' mode due to the heat from the lights. But at night, after the lights go off, the heater has to kick on. The problem is that the heater isn't hot yet, so it takes some time for it to heat up. By the time it does, the temperature in your tank has dropped due to the fans pulling the heat out into the outside air, and even after that, it takes the heater a while to pull back up 14 gallons of water, with the fans fighting it the whole way.

 

[liverock27]

Thanks Gmann1139. I think what I am going to do is test to see if the temp drop is due to the fans and evaporation over night, so I'm going to put a timer on the fans to run inline w/the daylights and see if that helps. If that doesn't correct the problem then tomorrow I will try the heater to see if the thermometer is off. Thanks for the help and I hope it is this simple. Have a good one.

 

[sigmachris]

Thermometer is off, I have one that is about 4 degrees off.

 

[liverock27]

Turned out that when I put my fans on a timer to run w/the 10ks the temp over night dropped less than one degree, so I think my temp problem is fixed.

 

[new2salt1]

Some company makes a heater with no knobs. It swears to never heat the water <76 or >78. AT night, I at 77, and during the day, it hits 80-81 (because of the lights).
It was a gift, so I dont know where to get it, but Ilike it.