Fluctuating Heater Performance

[InR reason]

This problem had arised when I decided to reconfigure my 20g to a tropical tank along with my 29. In it's simplest form, my problem has been maintaining a constant temperature. It's a pain in the *** to put it nicely. Heater equipment is as follows:

2.5 gallon: 25W Penn-Plax
5.5 gallon: 50W Tetra Whisper Pre-Set
20 gallon: 100W Tetra Whisper Pre-Set
29 gallon: 100W All-Glass Aquarium

The 20 and 29 gallon have constantly fluctuating temperatures, and beyond the normal 1 or 2 degree fluctuation. Even as the room temperature is a pretty stable 74-77 degrees will I find that my 20 and 29 will have temps drop from 78 to a 73 or 74 over the course of a few hours. I'd rather keep my tanks at a stable 78-80 degrees. The only heater that maintains a constant 78 is the one for my 5.5 gallon.
I would rather have a heater that is PRECISE and constant without worry of temp drops and the like. Can someone tell me why this is almost impossible to do with the heaters I have now. What is the best and most "worry-free" heater in your experience?

[Rallysman]

I like the Ebo and stealth heaters. They are the only ones that I've had consistently good results with.

[5xevy]

I use different heaters (titanium only, no glass). From what I noticed...if a certain heater states it's good for say 20-30 gallons and I have a 29G tank, I'm going to upsize the heater so it doesn't have to use its maximum capacity to warm the volume of my entire tank. Also, on my 29G, I moved the heater to the center instead of off to one side/corner, and that seemed to help quite a bit.

I would make sure your thermometers are accurate too. Who knows, maybe you need new heaters?

[leavundst]

I had nothing but problems with whisper heaters. Really happy with Rena. The last one that I got has a built in thermostat that is actually accurate.

http://www.aquariumguys.com/renaheater4.html

[Rbishop]

Stealth.

[webcricket]

Marineland Neptune or Stealth are good. I use 100 watt Neptune heaters in both my 20 gallon tanks with no problem. The 100 watt is a bit weak for 29 gallons. You might try getting a new 100 watt in one of the suggested brands for the 20 gallon, and try moving the old 100 watt into the 29 to see if you can get a stable temperature using both heaters (opposite sides of the tank).

[phaedraeos]

I REALLY like our Marineland Visi-therm Delux and Second Nature Acura heaters. I'd highly recommend both of them.

[J double R]

i use a 150w Guardian heater (no glass) in my 29 and it performs wonderfully.

[InR reason]

Guys thanks for your suggestions. I will research all the mentioned brands. Thank you. :)

[SmallFishi]

I also like Marineland Visi-therm I have one on my 20 and it's great... (DO NOT get their dual-temp ugh!)

I have a really nice Jager heater on my 55 gallon with a dial to set the temperature same idea as the visi-therm it too is good but I can't remember it's exact name, I think it was a little more money than the visi-therm.