In my quest to finally get my 55G planted tank up and running, I'm
going to shell out the cash and just buy the hood that maches my
All-Glass tank instead of making one. However, I'm not sure if I
should choose the twin tube (2 x 48" T8 tubes with electronic ballast)
or the triple tube (3 x 48" T8 tubes with electronic ballast) strip
light.

I would like to achieve a fairly low maintenance tank (ie: prune once
every month or two). I won't be using any CO2, however, I was planning
on using Excel and fertilizers on a regular basis. I'm perfectly happy
sticking to low and medium light plants but I definately want enough
growth to not get much algea.

But I can't decided on how much lighting. If I go with 2 bulbs I get
1.45wpg (counting 40 watts per bulb ... I know they only use 32 watts,
but they are equivalent to a 40 watt T12 bulb in light output which is
what was around when the wpg rule first started, so I'm assuming
counting them as 40 watt bulbs makes more sense). However, is 1.45 wpg
a little on the low side?

If I go with three bulbs I get 2.18wpg (again counting 40 watts per
bulb), which makes me think that I might have to start using CO2 in
order to avoid problems in the long term.

So what would you recommend?

Thanks,
Harry