You can use bog wood, but just place a little carbon in the filter (although this will remove the tannins). Basically the neons LOVE teac coloured acid water, and may even breed in such conditions in your tank. with the lighting in your tank, bog wood would not discolour the water too much. Soak it well in a bucket for a week first.
Also, there are commercial 'black water' treatments out there, but personally I dont recommend them, because it means yopur have to keep checking the water parameters constantly.