Appropriate heater size

[MarlinHooker]

What's an appropriate way to determine the size of heater required for my reef tank?

[Reefposer]

They are all rated per how many gallons they can handle. My heater covers the volume of my display and sump together.

[BeanAnimal]

Marlin... that is actually a rather hard question to answer, as there are numerous variables.

How many total gallons?
Target temperature of water?
Average room temp?
Min room temp?
How much evaporation?
Etc...

http://beananimal.com/articles/aquarium-heaters-what-you-need-to-know!.aspx Try this for a start and to get an idea of how to safely heat your tank.

[stingythingy45]

Very easy question
Shoot for 3 watts of heater to every 1 gallon water.
100 gallons x 3 = 300 watts of heater.

[BeanAnimal]

Very easy question
Shoot for 3 watts of heater to every 1 gallon water.
100 gallons x 3 = 300 watts of heater.

As I pointed out, the question is not at all that easy to answer.

3 Watts per Gallon can easily be far too much are far too little for an aquarium. If you take a look at the link to the article I posted, you will be able to see why.

A room 78 degree room with a 50 gallon tank kept at 78 degrees does not need a heater. The same room kept at 75 degrees causes a temperature differential between the tank and the room of 3 degrees. The same room kept at 66 degrees has a temperature differential of 12 degrees and needs over 4 times the heat to maintain tank temperature.

A tank sitting in a concrete floor will need much more heat than a tank sitting on a living room on a wooden stand.

A tank that evaporates a large volume of water every day will need far more heat than a tank with a tight fitting lid.

[cubsFAN]

Agreed. Not an easy question. In the summer I can rely on a 100watt heater in my 40 breeder to keep my tank at the right temp. In the winter I add a 150watt heater, and the 2 heaters struggle to keep my temp up because of my single pane glass in my apartment and a drafty front door. My suggestion is to use 2 heaters in case one fails and to use a temp controller to prevent overheating. I recently got the DA rkl and it is a pretty sweet deal.

[stingythingy45]

What ever,3 watts per gallon will get you close.
And btw,don't the heaters you buy have a thermostat?lol

[BeanAnimal]

What ever,3 watts per gallon will get you close.
And btw,don't the heaters you buy have a thermostat?lol

The 3 Watt per gallon rule-of-thumb is as arbitrary as a pinch of salt in a pot of stew. We all tell people 3-5 Watts per gallon, but understanding WHY we tell people that is rather important. Again there is a huge difference in the heating needs of a tank in on a concrete floor in the basement and one on a wooden stand in a temperature controlled living space.

The thermostats on aquarium heaters are extremely unreliable and subject to an extremely high failure rate. If you have TOO MUCH heater for your tank, a stuck heater will cook the livestock in a very short amount of time. If you know how many Watts you need and split the heating duty between several smaller heaters and a temperature controller, you can avoid almost all heater related tank failures.

Aquarium heaters are one of the cheapest components in your system but have the potential to due a tremendous amount of damage in a very short amount of time.

You may want to spend a few minutes and read the article at the link I posted.

[stingythingy45]

The 3 Watt per gallon rule-of-thumb is as arbitrary as a pinch of salt in a pot of stew. We all tell people 3-5 Watts per gallon, but understanding WHY we tell people that is rather important. Again there is a huge difference in the heating needs of a tank in on a concrete floor in the basement and one on a wooden stand in a temperature controlled living space.

The thermostats on aquarium heaters are extremely unreliable and subject to an extremely high failure rate. If you have TOO MUCH heater for your tank, a stuck heater will cook the livestock in a very short amount of time. If you know how many Watts you need and split the heating duty between several smaller heaters and a temperature controller, you can avoid almost all heater related tank failures.

Aquarium heaters are one of the cheapest components in your system but have the potential to due a tremendous amount of damage in a very short amount of time.

You may want to spend a few minutes and read the article at the link I posted.

Although I don't really know why you're making selecting a heater so complicated.I do agree that splitting the wattage need between 2 heaters is a very wise move.
I keep one 250 watt in my sump and a 150 watt in my tank for that very purpose.

[BeanAnimal]

Although I don't really know why you're making selecting a heater so complicated.

Aquarium heaters are one of the cheapest components in your system but have the potential to due a tremendous amount of damage in a very short amount of time.

Most aquarists will end up losing livestock or an entire system due to heater malfunction. Taking a few minutes to become informed (learn) about heaters and how they work, why they fail and how to properly size them can go a long way to preventing livestock loss. The more you know...

[cubsFAN]

Although I don't really know why you're making selecting a heater so complicated.I do agree that splitting the wattage need between 2 heaters is a very wise move.
I keep one 250 watt in my sump and a 150 watt in my tank for that very purpose.

i think my post shows a pretty extreme difference in wattage through the seasons. 100 vs 250 barely doing the job. now seeing that the op is from florida im sure that your method should work ok, but I think that philosophy is out like the watts/gallons in lighting. there are many factors. I have read many threads where the heater was what killed whole tanks. Just lookin out.

[stingythingy45]

i think my post shows a pretty extreme difference in wattage through the seasons. 100 vs 250 barely doing the job. now seeing that the op is from florida im sure that your method should work ok, but I think that philosophy is out like the watts/gallons in lighting. there are many factors. I have read many threads where the heater was what killed whole tanks. Just lookin out.

I live in N.E. so I know all about cold winters.
If you buy a good reliable heater it will shut off in summer and not be an issue till fall/winter arrives again.

[BeanAnimal]

I live in N.E. so I know all about cold winters.
If you buy a good reliable heater it will shut off in summer and not be an issue till fall/winter arrives again.

There is no such thing as a "good reliable" aquarium heater. The internal thermostats are extremely prone to failure.

[o0jmadr0x0o]

so is it safe to just overshoot and get the largest heater ( on a controler) u can. when its not needed its of and not wasting electricity, and when it does need to work i will get the water temp to where i want it faster?

[BeanAnimal]

No submerged electric heater wastes electricity, they are all 100% efficient with regard their function. A Watt is a Watt.

A 1000W heater running for 10 minutes uses EXACTLY the same amount of electricity and produces exactly the same amount of heat as a 100W heater running for 100 minutes or a 1W heater running for 10,000 minutes.

Putting a huge heater on a controller is better than allowing the huge heater to control itself... but you are MUCH better off splitting the duties into much smaller heaters and a controller and then using the built in thermostats as fail-safes.

Why? If the controller sticks on, the fail-safes on each heater will prevent the tank from overheating, even if one or two of them also stick ON. At the same time several of the small heaters can fail OFF and the tank will still have heat.

All of this is explained in the article I linked to in my first post.