How to Calculate Power Usage in your Tank

I did a little research, to find out how much running various types of equipment for my reef costs. This formula is used to calculate usage per month:

Watts divided by 1000 (1 KW)= Kilowatts

Kilowatts x Hours Per Day x Days in Month x Utah Power Rate (.0630290)=

$ Usage Amount

Here is an example of this with various types of lighting for instance:

250 Watt Metal Halide Bulb:

250 Divided by 1000 (Kilowatt)= 0.25 Kilowatts

0.25 (KW) x 8 (Hours) x 31 (Days) x .0630290 (Rate)= $3.90 per month

175 Watt Metal Halide Bulb:

175 Divided by 1000 (Kilowatt)= 0.175 Kilowatts

0. (KW) x 8 (Hours) x 31 (Days) x .0630290 (Rate)= $2.73 per month

55 Watt Power Compact:

55 Divided by 1000 (Kilowatt)= 0.055 Kilowatts

0.055 (KW) x 8 (Hours) x 31 (Days) x .0630290 (Rate)= $0.85 per month

The thing to remember is that $0.85 may seem cheap to run a power compact per month, but you should have at least 6 (or more) to light a 55 Gallon Tank, so that would make your bill $5.15 a month for these bulbs. In comparison, two 250 watt metal halides only cost $7.81 per month to run. A difference of only $2.66 a month.

Hopefully some of you will find this useful, if not fun to do.

To calculate usage of Pumps, etc, you need to find the watt usage the equipment using the following formula:

Watts = volts x amps

So: 120 Volts x 0.5 Amps would equal 60 Watts
Now use the formula at the top of the post to figure out how much it costs to run per month.

or you can be lazy and go here:

http://reefcentral.com/calc/tank_elec_calc.php

Quote: Originally posted by Sarnack on 19 February 2003

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or you can be lazy and go here:

http://reefcentral.com/calc/tank_elec_calc.php

 

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Dang... I thought I was making my mark too... Ha ha ha. Just Kidding. 

Thanks Sarnack. I'm lazy too, so this will be helpful.

Ryan

Just remember that nothing is 100% efficient, so an even better way to get a more accurate guessitimate is to find the amp rating on the ballast, then multiply the amp rating times 120, and this would be the "true" power rating.

For example, I have a 250 watt ballast (tar, Advance), the amp rating that it uses is 2.6 amps, so is we multiply 2.60 x 120, we get 312 watts.  Even though the bulb is only 250 watts, the rest of the energy is dissapated off as heat.  This is a reason the ballast get raging hot. 

If you ever noticed the electronic ballasts advertise a 25% reduction in energy, that because they are closer to actual 250 watts, or closer to 2 amps.

So the formula is watts = amps x volts, as stated above.

I know, I know just more info for you.

Who cares what it cost per month, if i put a cost on all (stress relief activites) it just causes more stress.

Quote: Originally posted by Suzy on 06 March 2003

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Hi,Guys! Our pumps have soooo much crap on 'em,if there used to be writing on them,I can't see it. Anybody have an idea how many watts a Rio big one uses? And a big heater? Any wild guesses? And Ryan,how much is your calculation? I'm just curious, 'cause maybe it's close to ours.....Thanks! Suzy P.S. Put me in the stress reliever catagory!

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The Rio has the wattage marked right on top of the case just below the model number. 

Calculating the heater usage on a daily/monthly basis is difficult.  How often does it come on and how long does it stay on for?  A lot of times this usage could be more or less neglected in the energy usage
cost calcuation (I figure mine runs about 1 hr per day...$0.30 to $0.50 per month).  Where the heater power requirments become important is when determining how many devices can be plugged into a household circuit, because when it does come on, even if only for a few minutes, it'll still be consumming the nameplated watts.

A household 15 amp breaker (120 volts) will power 1800 watts while a 20 amp breaker will power 2400 watts.  That's the sum of all components connected to the circuit.  So if you've got lots of light and big pumps on a 15 amp breaker, I've seen where the breaker will trip when the heater(s) come on (or when the vacuum cleaner is plugged into the circuit).

2 400 watt MH  800 - 1000 watts

2 big pumps  400 - 600 watts

(you've almost maxed out a 15 amp circuit at this point)