tank heat loss at night

[FishEggs]

Do you have the heater turned all the way up at night and it still drops?

Lets start with the fact that the heaters are rated for the tanks at an ambient room temperature of about 70 degrees. at those ratings most of them are able to raise the temp up about 15 degrees above room temp. if your heat is set down to 62 at night then you might not be able to get the tank up to 80 degrees at night. the light will add some heat to the tank but more than likely the room temp during the day brings the starting temp up so that the heater can bring up the temp the rest of the way.
I keep my house down to 60 to save on heating oil and i need to put 625 watts turned all the way up in my 40 gallon to keep the temp up at 86 degrees (treating for ich) but i use 400 watts regularly during the cold months instead of the 200 watts that says would be for a 40 gallon. during the summer i'll be able to cut back to the 200 watts since the house will be a lot warmer.
you could try covering the tank with one of those styrofoam coolers/warmers at night to keep the temp stable.

[Sahabo]

Well I keep the tank heater up at around 82 at night, and in the morning the water is still about 76. Maybe since we turn the house temp down at night, I need to get a 50watt tank heater to compensate for the room temp? I'll also look into some styrofoam for insulation.

[Purrbox]

Or you could just set you're aquarium to 76 degrees. That really is plenty warm for a Betta.

[An t-iasg]

Fish Eggs is correct - most heaters will bring tank water up approximately 9-10 degrees above an ambient room temperature. If the 25 watt heater is not giving you the results you want, you could get a 50 watt heater for the 5.5 gallon tank. I have a 75 watt heater in one of my 10 gallon tanks (a 50 watt heater is the "standard" wattage for this size tank). I had a 75 watt heater lying around, so instead of buying a new heater, I just used what I had. I have been checking it carefully and it is not overheating the water.

I use a digital kitchen thermometer to measure the water temperature. With any brand of heater, the numbers on the dial may not correspond exactly to the temperature that you get. I think I have my heater dial set to 76 or 77 (hard to tell since each degree is not marked) and it's keeping the tank a very steady 80.2 degrees. I believe 76 degrees is too cool for a betta.

[pitt420dude]

^ same here. I think we have the same brand marineland heaters too. I set it at around 74 and it's usually around 78.

[Sahabo]

Yes I think 76 is too cool for him...at that temp, he loses energy and clamps his fins. I picked up a glass therm today and hopefully I will make sure to get accurate results. I will try insulating and turning up the heater at night. If none of that works to my satisfaction, I'll get a 50 watt heater. I am really appreciating all the helpful advice. This forum rocks!

[Sahabo]

FijiWigi, you were so right about the floating therm! When my stick-on says 78, the glass floating says 81, which is almost exactly what I have the tank heater set to...sheesh. well, it will be interesting to see what the new therm says in the morning. Didn't get any insulation yet so I'll just use a towel over the top tonight to see if it helps.

[Sahabo]

So last night I turned the tank heater up to 84 and covered the top with a towel. What do you know...this morning when I woke up, the water was a steady 80 degrees . Turned the house temp up, turned the tank heater back to 82, voila! This might be my solution, at least for now. I might get a 50watt in the future which might eliminate the need for adjusting, but that will have to wait until I get a job. Thanks to all for you guidance and responsiveness!

[An t-iasg]

I recently moved my betta from a 5.5 gallon to a 10 gallon tank. I put the 5 gallon in the basement when it was empty, along with the equipment I was no longer using (but not the filter!) Today it was very warm so I took the tank outside and rinsed it out with the hose. I noticed that the heater I had in there was a 50 watt Visitherm Stealth. (I wondered where it went!) Anyway the point is I have used a 50 watt heater in a 5.5 gallon tank, and it worked out fine and didn't overheat the water. When I set up the new tanks, I measured the temperature every day at feeding time when the lid was open, and adjusted as necessary.

[An t-iasg]

That's good to hear!