Again , I may be wrong . If so , please explain why ....

Indeed, peat does work by leaching tannins into the water, thus acidifying
the water and also depleting the KH content of the water, making it
softer.
Dependent on the type of peat used (I use Irish moss peat), the pH is
dropped from a pH of over 8 to 5.5 and the KH drops from 13 to a
respectable
3. The colouring, although not to everyone's liking induces certain fish
to
spawn and also brings out a more intense colouration in the fish. I have
also found the tannins to be beneficial in the control of algae.

Not quite 100% right (he says to the man from whom he got the idea to filter
through peat in the first place!)

A Kh of 3 does not give a sustainable Ph of 5.5. After running through the
peat what I find is that if you look at the KH/PH relationship something is
amiss & the answer is that in going through the peat the water absorbs
massive amounts of CO2. This will come back out over time (fairly quickly)
so that water with a Kh of 3 will eventually settle to a Ph of about 7.5 or
so. Kh of 3 & Ph of 5.5 indicates a CO2 content of around 300ppm by my
calculations (!) whereas a "normal" concentration would be around 3ppm.

I also find that filtering through peat does lower the GH of my water - not
quite sure how its doing that but it does.

My tap water has a KH of around 9 degrees & a Gh of around 15

After its been through my peat filtering system it ends up at a Kh of 5 and
a GH of 9.5-10. A Kh of 5 gives me a Ph of around 7.8 which I then reduce in
my tank to 6.8 via CO2 injection (bottled gas system). I run the water
through the system till I get the Kh I'm looking for & then stop it - I can
set the Kh anywhere I like basically - it just depends on how long I leave
the thing running. As far as the colouration of the water is concerned,
after I've done the peat filtering bit I still have 40-50ppm of Nitrates in
my water (cos that's what comes out my tap) so I bought a Nitragon
Nitrate/Phosphate filter and I pump the water through that - a side effect
is that it removes almost all the colouration (and the Nitrates
obviously!). The Nitragon is rechargeable via dishwasher salt solution run
through it in reverse.

My pair of Dutch Rams are laying eggs in the tank (again!!) as I write.

Pictures of the contraption I use to do my peat filtering are on Mark's web
site......

hope that helps,

I.