Thanks Rob and Dave.

With a bit of messing around I was able to get:

GH: 10 DH -- 4-5 DH
KH: 8 -- 3

After adding peat:
pH: 7.2
pH: 6.8


With this kind of setup, as long I I keep the GH/KH of my water changes
the same, will everything be stable? (I know I'll have to watch for the
peat to exaust itself over time)