Peat Substrate, Mercury Vapor Lights, Flourish, etc.

Greetings from the great white north!!  I have been lurking on this list for 
a while and thought I would finally ask a few questions.

As an introduction, I have been getting into aquariums for a few years.  I 
started in Vancouver, which was nice as there were so many places to go for 
aquarium supplies.  Since moving Whitehorse in the Yukon -- a city of about 
22,000 people with no larger cities within 15 hours -- I am becoming used to 
the thought of having to special order just about everything I may need.

In Vancouver I had one planted tank.  I considered it quite successful, 
though it was too small at 20 gallons.  It was a low tech tank.  It had 
laterite in the gravel, I added no fertilizers, and I had a meager 15 watts 
of lighting.

My current effort has been with a 10 gallon tank.  I thought I would start 
with this to find something that works with the local water condition before 
moving to a larger tank.  Before I go on, I should add that I am on an 
extremely tight budget, so I am limited in what I can try to do.

This tank has not been going well.  The substrate is composed of about of an 
inch of vermiculite, mixed with a small amount of black topsoil.  I have 
about an inch of fine gravel on the top of this.  I have been using the same 
15 watt light I used on my 20 gallon tank in Vancouver.  The water here is 
quite hard and the pH is around 7.8.  I received a water analysis from the 
city, but have found it quite useless;  I have an analysis over several 
years and it shows that water  here changes continually and quite drastically.

I have been trying to grow wisteria in the tank, but the plants are starting 
to look pretty sad.  The lower leaves are falling off and there are yellow 
and brown spots on many of the leaves.  I have been adding a small amount of 
chelated iron gardening product and Epson salts to the tank but do not know 
how much of this I should add, or can safely add.

I am not sure what has gone wrong with the tank, but I would think it is a 
nutrient deficiency.

Now for my questions:

1.  There was talk a while back about Flourish, an aquatic plant fertilizer. 
 Has anyone out there been using this product and would you recommend it?  I 
am a little concerned that the product seems a little too good to be true.

2.  For the people out there that have used peat for a substrate, how is 
this done?  Do you mix it 50/50 with sand in the bottom half?  Do you mix it 

3. Though I have read of some people using mercury vapor lamps, I have read 
very little on how effective they are.  I saw an ad today for a 175 watt 
mercury vapor lamp for $60, including the bulb.  It seems like it would be a 
screaming deal if it was usable for a plant tank..

-- Darrell