Looking to replace ballast? HELP!

[fkshiu]

You'll use less electricity with an electronic ballast, but you'll also get less light output comparatively.

As Marie said, most SE bulbs can be run on an HQI ballast, but you will use more electricity, but (surprise, surprise) get more light output.

Magnetic ballasts are in the middle.

Sanjay's website is an extremely useful tool to compare various bulb/ballast combos. The most important columns are PPFD (aka PAR) for useable light output, CCT for colour rendering, and watts for power usage.