The original fixture uses two magnetic ballasts, one for each bulb, and relative starters. I purchased the following ballast from a hardware store, a Sylvania Quicktronic QT4X32/120 LP:

It's made to drive four 32W T8 tubes as the wiring diagram in the above photo shows (click to enlarge). The plan is to pair up the 4 wires so to overdrive the bulbs with twice the normal power (2x). First thing I removed the original ballasts and starters:

The wiring was simple as the new electronic ballasts don't require a starter. I screwed the ballast onto the reflector as the original ones were mounted, cut the wires to the desired length, stripped the tips and simply pushed them into the self locking holes in the endcaps:

Note: In the above photo, the return (yellow wire) is only connected to one of the two holes in the lamp holder. It is better however to make a jumper (a piece of wire) to connect the two terminals together or in some other way have the yellow wire connected to both pins on the lamp holder. This may prolong lamp life.

I took photos to compare the difference between 1x,2x and 3x. The first one is both tubes running at normal power (1x). Followed by 2x, then a side-by-side comparison with one tube running 1x, and the other running 2x followed by 3x:

Here's a closer look:

This is a comparison of the original setup using two old 40W T12 tubes and these same tubes being run at 2x by the new T8 ballast. The new ballast is only rated to run 3 40W T12 tubes so I wasn't expecting to see as much of a difference as with the T8 tubes:

The ballast didn't get warm at all during all the tests, the bulbs on the other hand did. At 2x the bulbs feel about as hot as CF bulbs while at 3x the bulb got quite hot, very quickly. I don't think a fan is essential running at 2x but probably a good idea to prolong the life of the bulbs and reduce the amount of heat over the tank. At 3x or 4x you will need some good ventilation and possibly some better endcaps. I'll have to keep an eye on the endcaps to make sure the extra heat does not make them brittle with time. Eventually I'll probably end up installing a small fan to prolong bulb life.

Further Reading:
- Overdriving F32 lamps, lumen outputs by Wayne Jones
- T8 Benefits by Wayne Jones
- ODNO - Lighting for less The Planted Tank Forum
- ODNO Discussion The Planted Tank Forum

Warning:

The modification described in this web page is for informational purposes only. I will not accept any responsibility if you attempt these modifications yourself, you do so at your own risk. This modification can damage/ destroy/ VOID the Warrantee and worst of all, cause electric shock. Seek the help of a professional or experienced person if you think you are unable to do these modifications safely yourself.