I see several problems here and will outline them below. Basically you
are setting up a rainforest type terrarium for temperate North American
plants; this is going to cause you some problems.
> I also have a glass lid but am not sure if I should use it or not. Is
> it better if I do.. I heard that some of the uv rays from the lights
> will be lost if going through glass. Is this true.
Yep, it's true, but your lights will not be putting out much UV anyway,
especially the short-wave UV that causes plants to color up, so don't
worry.
> As stated above, I have 2 48" tubes.. Do you think that it is better If
> I add 2 more tubes? I dont want to have too much.
You won't have too much light - don't worry. These are plants that want
to grow outside in full sun. Even 4 fluorescents is probably inadequate
for pitcher plants. S. purpurea might be okay if it is very close to the
lights (say a few inches), and Venus Flytraps will also survive that way
but prefer full sun outside to grow well and get their coloring.
> To add humidity I am building a water fall out of glass and adding some
> red slate to the sides of it to make it natural looking. This will
> hopfully help with the humidity requirements.
Well - there is a misconception that pitcher plants need steamy drippy
conditions (which is what this will give you). This sounds like a great
setup for Nepenthes, but Sarracenia will not thrive in it.
> I also have a old underwater filter which I used with my aquarium when
> it was set up. If I use it there will be a 1" gap bettween the dirt etc
> and the tank bottom.. Will this also help or is it just better to use
> the old way of a layer of spagium moss then a layer of gravel then
> dirt.
I would just plant with a mixture of peat and sand and forget about
gravel. Dirt? If you mean potting soil, don't use it - just use the peat
mix, and you can put live sphagnum on the top. Don't use dead sphagnum
for planting.
There is one other major problem here - these are plants that require a
winter dormancy and it is nearly time (I imagine that in Toronto, they are
well on their way). You don't need a terrarium to grow them; you can grow
them right out in the open air, and your local humidity in Eastern North
America will be plenty for them. What you need to be doing now is
preparing for dormancy - a cool but not hard freezing area, where you can
put your plants in their pots, and keep them just moist, not wet. The
dormancy requirement is vital, without it plants will languish and often
weaken and rot.
If I were you, I would use the setup you have for some Nepenthes and/or
some of the Australian rainforest Droseras; the high humidity and warmth
will suit them perfectly.
Good luck!
bob