Temperature Flucuations

[daisymoonbeam]

I can't seem to get the temperature in my tank to remain stable for about 3 days. It is the weirdest thing but it set right at 79.5 for several days and then for no apparent reason it jumps up to like 83.

I have two heaters 100 w each set to 78.5, one on each side of the back of my 46 gallon bowfront. They are the black steath one that most people I have talked to really like. I have exchanged them and tested them outside of the tank, not of course for three days, but really.

The temps around the tank are 74 right beside it inside the house and only 55 outside. This only seems to happen in very early morning and the lights have been out all night at that point so I know the lights aren't heating things up. In fact, the temps have only been fluctuating about .5 with the lights and all running.

I have two thermometers, one an American Marine Pinpoint that is supposed to be very accurate and also the Coralife digital both in the same place in the tank.

How am I supposed to have an accurate, even temp with all this and still nothing. I heard it wasn't good to have those kinds of flucuations and I am afraid if I don't do something it will go all the way down.

 

[Blown 346]

It sounds like one heater might be on the brink. I would trun one off for a few days and see if you continue to have that problem. If not you know what heater is or isnt causing the problem.

 

[daisymoonbeam]

Great idea, but I thought I had tried that. Both heaters are only about one to two weeks old.

I was under the impression that 100w alone was not enough to overheat a 46 gal.

I will probably try to unplug one again but it just seems like they should last longer than a week especially since I have already exchanged one of them for the same problem.

 

[Konadog]

Most heater controls are only accurate within +/- 2Deg. I bet you see your temp just after your heater is cycling off. Put one heater in a 5 gallon bucket then watch. Measure the temp right when the heater goes on, and just after the heater turns off to see the temp fluctuation.

 

[daisymoonbeam]

I can't seem to tell when the Stealths are on. Anyone know how? It doesn't have any lights on it (I think that is the stealth thing.

 

[Wryknow]

It's been pretty hot in Texas too. Is the tank temperature increase corresponding to an increase in ambient temperature?

 

[daisymoonbeam]

Don't think so. The temp in the house was 67 and the temp outside 55.

 

[rdanamorton]

does it stay at 83 for a while or drop back down by morning? i've been having a similar problem w/a 30g with 1 200watt renal cal heater. set at 78, my tank went as high as 83.5 by the end of the day. dropped to ~ 80 by the morning.
a LFS recommended removing my glass top to allow evap. and cooling. i did not do that because the heater tested ok in a bucket and the temp. seemed to stabalize around 80. recently it's gotten back up to over 83 again. so i'm likely to remove the glass top. today i'm running it all day w/just lunar lights to see how high the temp. goes.

i have a 36 in. PC w/2x 96 watt bulbs.

any one mention your tanks lid? i'm kinda curious now how most people deal with the lights beside fans on them.

 

[daisymoonbeam]

No really when I went to bed with tank lights off and just lunars it was 79.5 and had been that way for several days. When I got up this morning it had risen to 83. This is not the first time that has happened, it seems to be in 4 to 5 day cycles that is will stay at 79.5 (which is what I want) and then for no apparent reason jump up overnight to 83 or so.

Yes, I have a glass top, but I also have lights that say not to put them directly over open water (Coralife 2x96 Compact Flourescents) so taking the glass of doesn't really seem to be an option.

I wondered if maybe the heaters are not on in the daytime when the house stays around 72 or 73 and then at night when it is turned down to 67 or 68 they are having to come on and then just get carried away.

I have tried unplugging one of the heaters at this point is has been unplugged for about four hours, the lights have been on about4 hours and the temp has come down to 82.

Any more suggestions are welcome

 

[Blown 346]

I would keep those two heaters for emergencies, and get a good titanium heater with the actual temp probe and the heater control box. I bet your problems will stop.