Bottom posted.

"John Sankey" wrote in message
...
"My light hood has a sticker that says 30" / 20watt. Does this mean it is
only safe to use a 20 watt bulb in it and that I will need to buy a new
hood, specially made to handle VHO bulbs if that's what I want to go
with?"

If the VHO is marked other than 20 watts, it won't work with the
ballast in your hood. You are most unlikely to find a hood with a
ballast designed for VHO. (In fact I've never seen one with even
a rapid-start ballast here in Canada!) If you know your
electricity you could try swapping the ballast for one designed
for the tube you want, but it may be too large to fit and it will
probably overheat if the wattage is higher than 20.

I assume you want to increase your light level, but don't know
how experienced you are as a handywoman. Can you modify your cover
to take a complete reflector fixture designed for the higher
lighting you want?

If you are going to switch bulb types and can afford the initial cost and
the continuing electrical cost in money then get a good metal halide ballast
unit with reflector and 175 watt or higher bulb and hang the bulb over the
aquarium from the ceiling with a secure ceiling hook. 175 watts of light
should be enough ;-). Metal halide is very promising - now if only they
could wind the transformer(s) for them faster and cheaper so it all gets
cheaper....Good luck and later!