Right, I have space for a 4 foot fluorescent tube (36w) above 2 runs of wall cabinets (72W in total). They will be shining upwards onto a matt white ceiling about 2 foot above and can probably have a reflector underneath (silver foil).
They will be controlled by a dimmer, so at their full wattage want to be fairly bright. The room is about 4 x 5 metres.
Question 1: how bright will this be ? (perhaps in relation to incandescent bulbs).
I could get double ballasts and double up the tubes if required.
Question 2: if you have a double ballast, do you have the option of only using one tube ? If so, I might as well get double ballasts for flexibility.

Cheers,
Simon.