I have both the Rena Basic and Rena Excel heaters, the Rena Basics stink. Period. The temperature dial on the basic line is no where near calibrated properly, I have mine set to 72F and they Keep the tank(s) at 80F, that's not very accurate! The heater coils with also rust and turn brown and burnt looking overtime. Your better off buying a stealth or Ebo Jager.

This gets bad reviews for a good reason...

My rena 300watt heater was so inaccurate I gave up and now just use it on my water change tank. I set it at 70 and it keeps they water at 85 degrees. would never recommend!

I've had this for 4 years, no temp flux, no problems, I haven't touched the dial since the first week I put it in the tank.

It is still going strong and it has to work hard in the winter as my tank sits next to a window on a concrete floor. In the summer it probably hardly operates though.

So far its been great and i would recommend. I wanted to get an EBO JAGER, but I've heard the quality is not as good recently, and the price was high, so I got this heater.

Its been good for me and I'm suprised at the low reviews.

As many have said, these are not accurately marked as far as temperature goes - you still have to depend on your thermometer. But once they are set they do a wonderful job and I haven't had one fail on me yet.

Have a 300W in a 150g (along with a 100W of another brand). The Rena is always off by 3-4 degrees in my tank but you can maintain the right temp once you figure out the offset. The thermostat dial is awkward - not easy to be sure what temp it's set to when it's in your tank. Suction cups are only so-so (like most).

I only used this product once and that's it for me!! I had a 300 watt in a 90 gallon set @ 79F and it almost fried my show fish!! I came home to find my water temperature at 88F!! I quickly unplugged it and did a cool water change. Saved all my fish and bought a stealth!!

After about 1 month the coils were burnt and there was condensation on the inside of the heater! Will never do a Rena heater again!

I bought two Rena Cal Excel heaters on eBay for about $16 each, a good price. Some reviews on this site suggested that I would have to set the temperature a few degrees lower than I wanted that tank to be.

Initially, I installed them temporarily in small tanks, 1 a 10 gallon, the other a 20 gallon tank. It appeared that the reviews were right about the dial-in temperature being off by several degrees.

However, I thought about the size tank these were designed for and I was using them in a much too small tank.

I put both in a 55 gallon tank that will be for angelfish, set them both to 82 degrees, and watched as the temperature moved from the 76 we had it at slowly over a few hours to 82. Both were still on when it was at 81 degrees F. When it hit 82 and I checked, both were off.

If you use these in too small of a tank, expect them to heat faster than they can sense the temperature and consequently they will overshoot the temperature and stay on the high side. Keep them in a tank that is large enough for their wattage and you should have no problems.

I chose to use 2 of these in case something does go wrong down the road. If one sticks on, the other one will shut off at 82 and the broken one will have a hard time taking the temp up, buying me some time. If one sticks "off," then the good one will keep the temp from falling too fast.


At the "regular" price in a shop this would be a fair value, though a bit pricey.

But how much are

after two months of using this thing the coils were burnt black and it shocked two of my fish to death.

does the job and it has lasted after being droped and stuffed in closets and left on out of water.

I agree with other posts - avoid this product it is very difficult to adjust due to the poorly designed dial which is inaccurate.

Rena is a name you can usually trust but these heaters are awful. Not accurate and will not hold a constant temp. You have to monitor these all the time. To bad I didn't see these reviews until after I bought them. I'm going back to my Ebo's.

I bought mine in 2004. Within 2 months I exchanged it because just like some have said, it is not accurate. Mine was always higher by more than 5 degrees by what I had set it. I ended up with another, it basically does the same thing. My visi-therm and Ebo are way better....

I have two 200 watt Rena Cal Top Light Heaters in my 125. Both are set to 73 degrees, but keep a very constant 78 degrees in the tank. They are barely visible against the black background.

Always noticing temperature changes in the tank. Wouldn't recomend it.