Why are you switching to t5 if your trying to save money on bulbs? Have you ever had to replace t5 bulbs? They cost just as much as mh bulbs do. If your trying to save electricity don't switch to t5 cause there about the same watts.
Actually, for me a t5 setup would save substantially on electricity. I run three 400 watt Radiums on a six foot tank. The crux of it all is that many halide ballasts pull more/less wattage depending on the bulbs and/or ballast. For instance, my two 400 watt Galaxy ballasts on the left and right side of the tank drive the 400 watt Radium to 458 watts. I run a Blueline e-ballast in the middle and that runs the Radium closer to spec...around 380 watts. I only have them on for 6 hours per day and VHO actinic on for 4 hours per day.
Here's the math:
1. 1,300 watts of halide per hour x 6 hours = 7,800 watts = 7.8 kilowatts x
.15 per kilowatt = $1.17 per day
2. 320 watts of VHO actinic x 4 hours per day = 1,280 watts = @1.3
kilowatts x .15 per kilowatt = .20 per day
Over the course of a 30 day month this equals $41.10 to run halide with VHO actinic without actinics on with halides.
With respect to T5, my 26 inch wide sps tank would require an 8 bulb, 60 inch fixture to cover my 6 foot tank. Without changing the photoperiod of high light for 6 hours, the numbers are as follows:
1. 8 x 80 watt bulbs = 640 watts per hour x 6 hours = 3,840 watts = 3.85
kilowatts x .15 per kilowatt = .58 per day
2. 2 x 80 watt bulbs = 160 watts per hour x 4 hours = 480 watts = .5 kilowatts per day to simulate dusk dawn x .15 per kilowatt = .08 per day
Over the course of a 30 day month this equals .66 per day x 30 = $19.80
Halide = $41.10
T5 = $19.80
T5 would save me $21.30 in electrical consumption per month or $255.60 per year.
Most metal halide sps reefs change out their bulbs at 10 months...some sooner. My sps don't look as good after 10 months without a bulb change. The same can be said for VHO actinic and those with ATI Powermodules that have exceptional reefs. It's safe to say that you will/should change out your bulbs within a year for optimum coral color, growth and avoiding lighting spectrum shift.
3 Radiums x $85 per bulb = $255 (free shipping...yeah!!!)
2 VHO Actinic x $28 per bulb = $56 (free shipping if bought with Radiums)
Total of $311 per year
8 bulb T5 replacement as per Reefgeek with shipping $204 Total
So, the total cost of running a Halide and VHO actinic 6 foot tank for me barring a ballast blowout or premature bulb failure is $804.20
The total cost to run an 8 bulb ATI Powermodule per year is $441.60
T5 wins by a whopping $362.60, a 45% savings in electrical consumption and bulb replacement cost. The numbers translate into smaller tanks as well. Although I love the shimmer of my halide lighting system, I may definitely be switching to t5 simply to save a boatload of money that could be spent elsewhere on the tank or on other hobbies. Switching to LED would have an 8 year break even point to save on the cost of the LED lighting system and electrical consumption savings. Trust me....I did the math.:headwally:
In the end everyone has to decide what they like. I've seen some great halide tanks, and some beautiful and equally stunning t5 tanks. I'm not ready to make the switch to LED for obvious reasons, but if I'm in the hobby 7 or 8 years from now when the kinks are all worked out I may be willing to give it a go.
I hope this helps someone who actually read my whole post.
