6500k is the color temp, doesn't tell us anything about the power it will use. What's the wattage? (actual not "equivalent") And how much is "a lot" to you?
Don't worry you will be fine. I have five 13 Watt CFL bulbs and two 23 Watt bulbs running. So that's 111 Watts of power. I have it running 24/7 currently. So in a given day I am using 2664 watts a day or 2.7 kilowatts hours. My power company charges about 0.13 dollars a kilowatts hour. So that means that it costs me 0.35 dollars a day or $10.53 a month! So to figure out what you are using do the following: 1: Find the true wattage usage of the bulbs you are running...not equivalent! 2: Multiply that buy the number of hours it is running. (18h, 20h, 24h) 3: Divide that by 1000...this will give you kilowatts hour which is what your power company charges by. (This will be usage per day since we calculated what you are using in a day) 4: Find out what your power company is charging you per kilowatts hour - via your bill or online 5: Multiply cost per kilowatts hour by your usage. Voila! You have your cost per day! 6: Muliply that by 30 and you now have cost per month...assuming you do not change anything. I hope that helps!