metal halide ballast.

[slandis3]

Does anyone  know how much of a differance there is between a cap and coil ballast and a electroinc one? Will you save enough money on your electric bill to cover the extra cost? I dont care about the heat they give off, just how much do the cost to run.

[Viggen]

I did a quick yahoo search & gound this

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Electronic vs. Magnetic ballasts
Eley et al. (1993) describe the advantages of electronic ballasts:

Electronic high-frequency ballasts increase lamp-ballast efficacy, leading to increased energy efficiency and lower operating costs. Electronic ballasts operate lamps using electronic switching power supply circuits. Electronic ballasts take incoming 60 Hz power (120 or 277 volts) and convert it to high-frequency AC (usually 20 to 40 kHz). Electronic ballasts are more efficient than magnetic ballasts in converting input power to the proper lamp power, and their operating of fluorescent lamps at higher frequencies reduces end losses, resulting in an overall lamp-ballast system efficacy increase of 15% to 20%.
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I use to use the Magnetic style & after going with a electronic one I will never go back.  The electronic ones seem to look beter & turn on the bulb more consistanly.  I have never compared actual power consumption but when there is heat power is being waisted.  So in time it does make sence a electronic one will pay off, I just have no clue how long it takes.

After talking to Verper I am also convinced the Luminarc III reflectors are a must for any MH bulb.  I had the normal spider reflectors & the difference between those & the luminarcs is simply amazing!!!!

[slandis3]

I am running 2 175w mh on my 65g, 2 250wmh on my 120g.  All of which are electronic. On my sump and mu indoor pond, I amr running a total of 4 175w mh with cap and coil ballast.I can usaully fond used advance electronics on ebay or mendelson's for $30-50 shipped. I wounder if its worth buying the electronics or not.

[verper]

I wounder if its worth buying the electronics.

Short answer - yes.  15-20% a month over a few years adds up.  And I know you said you don't care about the heat, but if the ballast are inside an air conditioned room, you will need to factor the savings from extra a/c also.

Another thing to consider, electronic ballasts will run almost any light bulb.  The ones I have claim to be able to run any 400w light on the market.