# Heater watts per gallon



## GraphicGr8s (Apr 4, 2011)

A few months ago I was looking at heaters myself. I wound up getting them from foster and smith. Now for the point. I looked at 3 different heaters. And three different manufacturers had 3 different size heaters. My feeling has always to use two heaters at half the wattage each. Then if one sticks closed it's no big deal. If one stays open the other will at least keep the tank from getting too cold. Of course ymmv


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## kevmo911 (Sep 24, 2010)

Yeah, 3-ish isn't a bad idea for probably 10-15 degrees. If the tank is somewhere cold (like a basement) or you have warm-water fish (like discus) you'll want to increase the wattage.

But I agree with splitting it up between a couple heaters if you don't mind the clutter. All heaters will bust, and unfortunately, all too often, they bust in an "on" kind of way. That said, there are better heaters and worse heaters. Consensus is just go with a Jager.


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## Dx3Bash (Jan 9, 2013)

If you do use the larger single heater you could always add a second layer of control and protection like a Heater controller. I'm currently looking to add the Finnex Max-300 Digital Aquarium Heater Controller on my aquarium. Never used one before but it can't hurt. I like to error on the side of safety and caution.


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## CrypticLifeStyle (Jan 16, 2013)

In my 55's & 75's I run a 200 watt on each end. In my 29 a 150 & 2 300's in my 180. Closer to the intakes, faster the heat distributes.


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## exv152 (Jun 8, 2009)

If you go with the two heater idea, which is a good one, make sure you don't over do the wattage. Otherwise the heaters will be going on and off more often, making them wear & tear faster, increasing the chance of failure. I'd get two jagers and aim for 3-4 watts per gallon total. If you add a controller to that, that's even better.


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## BBradbury (Nov 8, 2010)

*Heaters*



Soup12 said:


> WHat is general rule for watts per gallon....
> I was always told to air on caution by using lower watt heaters just in case they get stuck on it be less likely to fry your fish. I was told around 3 watts per gallon rule.
> 
> 40 breeder - using 125 watt
> ...


Hello Soup...

Your tank will need 5 watts per gallon of tank volume up to 30 gallons. Tanks over 30 gallons will do fine with a heater or heaters at 3 watts per gallon.

The larger tanks will need two heaters placed at opposite ends of the tank for good heat distribution.

This is what I generally do. But this is just one opinion.

B


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## jaliberti (Dec 5, 2015)

CrypticLifeStyle said:


> In my 55's & 75's I run a 200 watt on each end. ... Closer to the intakes, faster the heat distributes.





BBradbury said:


> ... larger tanks will need two heaters placed at opposite ends of the tank for good heat distribution. ...


Yes, I know, the last post on this thread was 3yrs ago. But I just googled _aquarium heater watts per gallon_ and this thread was the 2nd hit (ThatPetPlace was 1st). I just wanted to add that of the 84,347 members on this forum there might be maybe 3 of us (LOL) that don't use aeration/filtration (other than what live plants provide) and so even tanks smaller than 55's, e.g. 40g breeders, 20g Longs, etc, which are of stagnant water can benefit more from multiple smaller heaters placed at intervals rather than a single large heater placed in the center. Peace.


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## Freemananana (Jan 2, 2015)

I also want to add that wattage is dependent on ambient room temperature. For instance, you need less heat in Florida than in Washington state. I've heard 1-2w per gallon for the 1st 10 degrees above room temperature and 3-4 for the next 10 degrees after that. Anything more would require a large heating circuit.

Secondary tip, using a heater controller will prolong your heater life according to some. By using the controller to turn the heater on and off, you prevent wear on the heater's switch and could prevent it from sticking open or closed in the future.

I also prefer multiple, smaller, heaters than one large one.


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## Nordic (Nov 11, 2003)

Why not look on the box of the heater, I know even the cheap Dophin heaters I use have a table on the side for recommended heater vs. tank size


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## mistergreen (Dec 9, 2006)

5 watts per gallon is generally the rule.


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## flight50 (Apr 17, 2012)

Back in early 2000s when I jumped in the hobby, I was told 2-3 wpg. So I continue to do so. Ambient temps does have a lot to do with it as well. You don't want a heater with high watts though. Reason being, you will short cycle the heater. What does this mean. It means that your heater will turn off and on more frequently than a more adequately sized heater. It's like having an oversized AC in your house. If the unit is too big, it will cool to quickly and you will have moisture and condensation problems. Same with a heater. I will heat up quickly and shut down quickly. I hear of a lot of heater failures from being on this site but in almost 15 years, I have not had one yet. Nothing last for ever but I can't tell my Ebo Jagers that, lol. Typically on big tanks, I go with two smaller heaters in opposite corners for more evenly distribution of heat.


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