Thanks everyone for your kind words. I hope to see the photos of your precious tanks too.

The filter is external Jebao 615 (or 618 - can't remember). I just use regular downlights Philips 18w daylight (it says 100w output) but I am not too sure which is the exact wattage. What I do is to use a 4" drain pipe, saw the drainpipe by half horizontally and then tie the lights to holes drilled at the pipes. All DIY. This is easy as the Philips downlights comes with built in ballast and thus there is no need for one anymore. I do not think the method is suitable for larger tanks though as the radius of light produced by the short downlight is rather small.

Perhaps later I'll try to post some photos of my office tank to illustrate what I mean.