In alt.aquaria James Smith James wrote:

Im always open to improve my knowledge. I thought that a "promotes plant
growth" tube would be right to support improved plant growth. Obviously I
was wrong!

Well, see that's the problem with just relying on the labels on the box or
things like color (eg 4000k) or CRI. None of these are truely indicative
of how much red spectrum the bulb provides. And they can be quite accurate
in saying it would promote plant growth because it provides plenty of blue
spectrum which plants also require in photosynthesis.

The Interpet Triton spectrum is listed he
http://www.thegoldfishbowl.co.uk/lighting.html. It has a slight increase
above 650nm but nothing significant. The triton is quite a commonly used
"fish only" tubes used by the stores. It might be a good one to use in
combination with a plant tube?

That looks like a pretty typical fresh/salt combo lamp spectrum. See,
corals (salt) like blue and blue is important to plants, so it's very blue
heavy. There's also a minor spike around 700nm for plants. The Interpet
Beauty lamp listed on that page might also be a good candidate.

After having another study the easiest way to fit is to keep the existing
30w T8 fitting mounted in the center of the tank, and add a T5 tube (39) to
the front of the hood. This would then give 30w T8 and 39W T5 - or a total
of 69w in 29gal (2.37w gallon / 20w sq foot) which is well within the target
lighing requirments of 2-3 w gallon and 230% more than now. Or would going
for 2x T5 be the better option?

Well, the only reason you might want to go with two T5 bulbs is if you're
planning to pay for a two bulb ballast. Then you'd only have one ballast
instead of two if space for the ballasts is a concern. However, there's
also advantages to running two ballasts. In all my tanks with two
ballasts, I have the weaker light come on first and go off last to create
a little bit of a buffer zone between no tank lights and full tank lights.