With a GH of 8 I would expect the same or less for KH, so pH will tend to lower as the tank matures. This will suite soft water fish like the tetra, rasbora, and many others. Avoid livebearers, they would not fare well in soft water and you said you didn't want them anyway, so that's good.
And I agree to forget Tiger Barb, in a 30g to be "healthy" they should be on their own in a group of 8-12. That's fine if that is what you want, but if you want more fish species, please forget the Tigers. And Serpae Tetra too before you come to them, very similarly aggressive fish.
We have fish profiles, second tab from the left in the blue bar across the top, you can search possible fish there. Characins (tetra, etc) and Cyprinids (rasbora, etc) would be the main categories for a 29g, plus catfish. Info on numbers needed (for shoaling fish), compatibility, water preferences, etc. are in the respective profile.
With a 29g, the options are so numerous. Remember the smaller the mature fish, the more you can have, and several groups of small tetra/cyprinids can be quite interesting and beautiful in a ploanted 30g tank.