Suggestions for a Good SMALL heater?

My Hydor Theo 25w has been great. It has an adjustment dial, and I've successfully used it in 1-gal, 2.5 gal, and 7-gal cory fry tanks. Never overheated, and kept the temp stable.

I like this brand, too. I have the Hydor Theo 50 in a 4 gallon. It's fully submersible and shatterproof. The temp. is always stable, something I was pleasantly surprised by. I had expected temp fluctuations with a small tank. I would have gone with the 25 if I'd had the option -- 50 seemed a bit much -- but the 50 came with tank and a bracket to hold it off the acrylic. So far, so good. I couldn't be happier with the results.

http://www.aquatichouse.com/Pumps_files/hydor heater.asp
 
I have been using an under gravel heater on my 2.5 betta tank, keeps it at 80º steady, and It is hidden under the sand so it is not visible. Though not a fan of Petco I did buy this there.
http://www.petco.com/product/102429/Hydor-Mini-Aquarium-Heater.aspx

here is a pic of his little world.
100_0535.jpg
 
Either size should work but you have more models to choose from in a 25. As someone said, (Mgamer20o0?) you want one that you can adjust to suit your aquarium residents, not a single temperature pre-set.
 
Either size should work but you have more models to choose from in a 25. As someone said, (Mgamer20o0?) you want one that you can adjust to suit your aquarium residents, not a single temperature pre-set.
Usually true, but since it was for a betta tank, I don't think it is as much of a concern.
I have both of them in my betta tanks. I like the marineland one because it is preset and have not had any problems with either of them in my tanks.

The other is nice too because it can be put under the gravel, my only concern if it is the one I am thinking is that it doesn't actually turn off, it is set to raise the water temperature by a set amount and if you read the directions it says to "monitor temps and if needed unplug heater" which I am really not cool with.
We also have one of the Hydor 25 watt heaters. no problems but it is bulkier than the marineland especially in a 2.5 gallon
 
Most adjustable heaters you set the temperature. I don't think I've ever seen one where you set the heating power manually. I'm sure they could be designed that way but I've never seen one.
I take it back, when I first started and they didn't make heaters, we used incandescent bulbs and used time and wattage to move tank temperatures to where we wanted them. It was not very convenient and a 3 or 4 degree daily swing was not unusual. The things that are made to be heaters always seem to have temperature and not power settings. Something that goes under the gravel is a thing I've never used so there may be an effect there that would be more variable because of the transport time to the water and the sensing point vs the thing you are trying to control. I have no experience with such a heater.
 
ghjhreed,

I have an Ebo Jager that is old, something like a LZ200 (200 watt model)... You set the heat by moving a dial rated from 0 to 9... It took a bit to get it set, I just put it in 80*F tank and twisted till the heating light went on, then back till it just went off. Been holding my tank at 79.3*F luckily. Got a Hydor ETH on the way to replace it, the Ebo Jager doesn't seem like a good enough heater for the room the tank is in, its always on.
 
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