Mercury Vapour lighting & curled leaves

I am forging ahead (slowly) with the setting up of my new Paludarium. In
the process I've been considering lighting. I know about florescents and
Metal Halide but looking in my Denerle (sp?) book (courtesy of the TAG) I
see they use Mercury Vapour lights. So I got out my yellow pages and called
a commercial company that sells these bulbs and I find out these things.

They aren't hot like Metal Halide and they are energy efficient and cheap
to run.

A 75 watt bulb (two should be enough for my 4 ft tank) costs $110 Canadian.
The necessary ballast costs $35. Both the bulbs and the ballasts last for
many years inside or outside. I was told they are easy to hook up -- no
harder than florescents and maybe easier.

They come on slowly and fade when turned off, simulating the sun going down
without timers.

I would have to make or adapt a pendant light fixture to hold the "mogul"
socket the bulbs need but other than that they sound pretty hassle free and
better than metal halide.

How come nobody in North America uses these? Is there some terrible flaw
that I am missing?


I have two plants in my aquarium that insist on growing with their leaves
curled along the length. One is A. renekii and other is a water cabbage.
What does this indicate? Not enough light for them? Perhaps missing some
nutrient. I'd really like the leaves to flatten out.

in Vancouver