# Aquariums and your electric bill



## dugganhayes (Mar 18, 2005)

Does anyone know how much an aquarium ups the electric bill?

For an example a 75 gallon with a 250 watt heater, generic light strip and maybe a canister and a hob filter. What would that cost? A lot?

Could you compare it to running a computer on day and night, or is it closer in price to running your air conditioner.


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## Puulu (Mar 4, 2005)

Depends on how many amps all that added together draws. I doubt all of the aquarium junk would add up to the pull of a air conditioner, compressor, and the two fans required for it to operate. But the A/C will shut off now and then as opposed to a filter or lighting on an aquarium.

Running a 1500gph pump might add $5-10 on your monthly bill.

Someone running a reef tank with metal halides, fans, and probably a chiller would be drawing some wattages' :lol:

Running a "stock" tank with lighting, heat, and filtration probably isn't adding $ 2-5 a month.


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## jmccalip (Mar 13, 2005)

Puulu said:


> Depends on how many amps all that added together draws. I doubt all of the aquarium junk would add up to the pull of a air conditioner, compressor, and the two fans required for it to operate. But the A/C will shut off now and then as opposed to a filter or lighting on an aquarium.
> 
> Running a 1500gpm pump might add $5-10 on your monthly bill.
> 
> ...


I think a 90,000GPH pump might be a tad to much for a 75g. :wink:

Btw: How much does your electrical company charge per KW an hour(or w/e). Mine just went up to 11 cents :x


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## Shwaine (Apr 27, 2004)

You can actually come up with an estimation of how much electricity the tank will use every day with a little more information and a little guestimation. First the easy stuff that does not require guessing. Take the wattage of your filter motors, which should be imprinted on the motor, and multiply by 24. Then take the wattage of your lighting and multiply by how many hours you will have it on. Add these two numbers together and divide by 1000. This will give you the KWh for running the filters and lights for one day. Multiply this by your utility rate to get the cost per day of running the filters and lights.

Now the guestimation portion... the heater costs are more difficult to calculate because it will depend on how often the heater comes on. The amount of time the heater is on depends on the room (ambient) temperature compared to the desired tank temperature. The closer these two are, the less often the heater will come on. If you want an upper bound on costs, then just take all the guesswork out and say the heater is on all the time and multiply the heater wattage by 24 then divide by 1000 to get the KWh. Even though this is unrealistic, you'll at least know the heater will never use more energy. Otherwise you can try to estimate how many hours in the day your heater will be on and multiply the heater wattage by that guess.

So here's an example. Let's say you have 80W of lights on 12hrs a day, an AC70 HOB with a 6W motor, a Eheim canister with a 25W motor and a 250W heater. Here's the calculations:

Filters: (6W + 25W) * 24h = 744Wh / 1000 = 0.744 KWh per day
Lights: 80W * 12h = 960Wh / 1000 = 0.96 KWh per day

So that's 1.704 KWh per day for the filters and lights. At a $0.11 rate (which is my current rate too), that's about $0.20 a day and $6 for a 30 day month. Now onto guessing on the heater:

Heater (max): 250W * 24h = 6000 Wh / 1000 = 6 KWh per day (max)
Heater (12h): 250W * 12h = 3000 Wh / 1000 = 3 KWh per day (12h)
Heater (8h): 250W * 8h = 2000 Wh / 1000 = 2 KWh per day (8h)
Heater (4h): 250W * 4h = 1000 Wh / 1000 = 1 KWh per day (4h)

So the heater at most uses 6KWh per day, but more realistically will use 1-2KWh per day unless the room the tank is in is very cold. Together with the calculations for the lights and filters, you'd use about 2.7KWh to 3.7KWh per day. That's about $0.30 to $0.40 a day or $9 to $12 for a 30 day month. At most if the heater was always on, it would be 7.7KWh per day, for a cost of $0.85 a day and $25 for a 30 day month.


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## bigstick120 (Dec 26, 2004)

Great post Shwaine, I was wondering how one would figure this out. I will have to figure the total cost of my tanks


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## Jode (Apr 17, 2005)

Kudos to you Shwaine my brother and I made similar calculations ourselves. It really just takes some basic math skills to figure this out, but I know that most of us including myself hate math and can't stand even trying to take on these kinds of projects. To be honest, my brother did all of the math work, I just gave him the figures and stood by as he worked it all out 

Truth is though, that most of us should be able to do this with our High School math skills....if we can even remember them!

Even a 125 Gallon, with several flourescent lights and a wet/dry filter and heater will still only cost a few dollars a month.

A word of caution: If you're a reef tanker with those metal halides - fogedaboutit!


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## dugganhayes (Mar 18, 2005)

Wow, just what I asked for! Great informative post. I think it should be a sticky.


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## Shwaine (Apr 27, 2004)

Yeah, it is somewhat basic math but something I had to specifically calculate for my tanks a couple years ago. I had a roommate claiming the one 40g tank I had then was costing over $50 a month. Whipped out those calculations and proved her wrong, particularly since I didn't have to run a heater back then as the tank room was usually 80-85F. Turns out another roommate who moved in right around when I set up the tank was really bad about leaving lights, fans, computer monitors, etc on and that accounted for most of the increase.

As a side note, these calculations also show why it's the heating that's the big energy cost in most fishrooms (except for those located in warm climates) and also why most people heat the room and not the tank for fishrooms. About half the cost or more of running a single tank in cold climates is just the heater. Translate that to many tanks in a fishroom and imagine the costs if trying to heat each tank individually. Much cheaper to insulate the fishroom and keep it warm via some energy efficient room heating method.


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## JoseRiv (Dec 15, 2004)

Well said! For instance, I have a 300 watt heater, that's the equivalent of running four incandescent bulbs at 75 watts each.


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## Puulu (Mar 4, 2005)

I've kept fish out in a unheated building in the winter time. I had a 30L, 55g, and a 20g all in a enclosed wood cabinet with seperate heaters. They stayed snug as a bug.

It's possible to insulate a tank to a certain extent. Having the foam on the bottom helps a lot. Water is very thermally stable once it's at a certain temperature, it takes a lot of BTU's to change it one way or the other. A heater probably doesn't use as much juice as one might think.

You would probably have to keep a room temp. set at 98 deg. in the winter to have water in an aquarium be 78 deg. I'm not gonna set around in 98 deg room lookin at my fish! :lol:


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## Shwaine (Apr 27, 2004)

If you set a room at 98F, you're going to end up with 98F cooked fish in the tanks. Temperatures prefer to come to an equilibrium and absent a heat source a tank will come into equilibrium with the ambient temperature. How long that takes is dependant on insulation factors, but eventually it will happen. With most of my setups, an ambient temperature from 75-80F is sufficient to maintain good temperatures within the tanks. And for some reason my most recent apartments like to hover in this temperature range even mid-winter, so my heater costs are minimal. But not everyone lives in such a moderate climate as my current location, so for others heating tanks can become a big cost.


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## Puulu (Mar 4, 2005)

Water is what makes an evaporative air conditioner work. Evaporation. A glass of water setting on a counter will never be the same temperature as the air around it. It will be cooler.


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## Shwaine (Apr 27, 2004)

The effects of evaporation will not be enough to keep a tank in a livable range in a 98F room. I know this from experience with a roommate who turned off the AC and allowed the room with a tank in it to reach similar temperatures. The effects of evaporation in a fish tank are usually minor, maybe ~2F assuming the tank is open topped. In a closed top tank, the air between the water level and lid reaches humidity saturation far before evaporation cools the tank off any appreciable level.


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## Puulu (Mar 4, 2005)

I agree, Humidity would certainly play a part. At 98 deg (outside air temperature) a heaters electrical consumption wouldn't be an issue because it wouldn't need to be plugged in. If somebody lob's off a section of their garage and builds a fish room that is well insulated, it could be heated very easily with a small space heater..

Keeping the tanks cool on the other hand could be a problem without adding A/C. On the tanks I had outside it would hit 105deg and I had to add fan's to stay around 94deg!

As you may have guessed by now I have a picture of water setting in my centrally cooled kitchen right now and the water in that Picture actually is about 2 deg warmer than the surrounding air. I think the problem arises when we add a couple little evaporative coolers called Emperor 400's.

I've been in stores in the winter time that heat there tanks with the same heater as the building. It's so hot in there I could hardly breath. I think the money saved from heating several tanks this way is actually in the form of not having to buy heaters.

I've busted a couple in the past three month's myself.


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## Puulu (Mar 4, 2005)

Just an interesting little foot note. I have a 110g insulated wooden box with a pond liner wrapped in ceder fence pickets. I use it to age water for water changes. The water in it has been setting there for a week. Outside air temp right now is 92 deg. The temp in this pond is 72 deg. according to three different sources of thermometers. The pond remains covered with a piece of styrofoam insulation.

This pond is however setting on a cement slab. Maybe it absorbes the coolness from the ground below.

I also have a 10g guppy tank setting next to the pond on a stand. Both containers and temperatures are in the shade under a tree. Guppy tank has a Tetra 60 filter on it. With the outside air temp at 92Deg the temp in this guppy tank is at 82 deg. I would say evaporation and humidity have a very large role to play in the thermal qualities of water.

Having an enclosed light hood on a tank would have a large effect on the time a heater would need to run.


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## mdstark (Jul 13, 2004)

You have to compare the water in the tank to the average outside temperature over a period of days. You can't simply compare the current water temperature to the outside temperature in the heat of the day. I'm guessing that the average outside temperature in your area over the last 48 hours is significantly lower than 92 degrees. Water holds heat very well. Since your 110 gallon is insulated, it will hold its temperature even better- but it will still eventually equalize with the average outside temperature. Your 10 gallon tank does not have the insulation or the volume of water as your 110 gallon, so it will fluctuate according to the outside temperature more rapidly. However it will still likely remain lower than the outside temperature during the heat of the day simply because it started at a cooler temperature and hasn't had time to equalize.


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## stslimited84 (Oct 5, 2007)

great thread! 8)


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## dwschacht (Jan 8, 2007)

I might add my 2 cents.

I use no heaters. I also live in Texas. In the winter I have my thermostate set at 70 degrees. In the summer, 76. My tanks never fell below 71 degrees in the winter and will reach temps up to 81-82 degrees in the summer.

I believe the higher temps than the room are caused by filter pumps giving off heat and lights giving off heat. I have also never lost a fish to temperature.

None of my tanks are insulated.


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## teqvet (Mar 24, 2008)

Puulu said:


> Just an interesting little foot note. I have a 110g insulated wooden box with a pond liner wrapped in ceder fence pickets. I use it to age water for water changes. The water in it has been setting there for a week. Outside air temp right now is 92 deg. The temp in this pond is 72 deg. according to three different sources of thermometers. The pond remains covered with a piece of styrofoam insulation.
> 
> This pond is however setting on a cement slab. Maybe it absorbes the coolness from the ground below.
> 
> ...


I was going to say, it's not fair to compare the pond to inside tanks, as the water is able to draw the coolness from the ground. The ground stays very cool in the morning even when the sun is baking already, and at night it's quite very warm when the cool night air rolls in. This causes some great foggy sceneries in the country.


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## shocker123 (Mar 20, 2011)

Neat thread, i thought i would bring back up


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