MH cost to run ?

[warren thomas]

has anone figured out how much they pay a month to run their MH bulbs im just woundering the difference between 250 watt and 400watt . i plan to run 3x6500 iswaki but not sure what watt to go with . it seems that i can upgrade to 400watt for a small amount of money and im sure the tank would do better with 400 vrs 250 its a 125 rr by the way .and i want to use 2x160 vho for actinic . thanks !

[bdr127]

If you're just looking for the difference in electricity, that is easy enough to calculate.... If you are looking for long-term cost to replace bulbs and such, that is a different story....

Say you run your bulbs 10 hours per day (for a nice even number), and you said you had three bulbs. That comes to 30 bulb hours per day. If you have 3x250W, that is 250W x 30h = 7500W/day or 7.5 kWh/day. If you have 3x400W, that is 400W x 30h = 12000W/day or 12 kWh/day.

The cost of electricity varies throughout the country, so you need to look at your electric bill to see what your kWh charge is. Say it is as low as $0.10/kWh.... 3x250W would be 7.5 x $0.10 = $0.75/day or ~$22.50/month. For 3x400W, it would be 12 x $0.10 = $1.20/day or ~$36/month. If your electricity costs $0.20/kWh, then that is 7.5 x $0.20 = $45/month and 12 x $0.20 = $72/month, respectively.

Check out how much your electricity costs and use the math above to calculate what it should cost you.

[minh_han]

If you end up changing your lights from 250 to 400, I'd like to consider getting the 250's from you. I originally ordered 3 250W from the LFS guy (Jose from Bloomfield Aquatics) and he assured me that the MH's were 250. Well, I didn't find out until later that the lights and ballasts are 175, and old at that. I just ordered two 12000K lights to replace the ones that I have, and I'll get the last bulb later. But, some time, I want to upgrade to a higher wattage.