hard water & pH

You could do some of the shelldwellers in a 10gal, check out Neolamprologus sp.
 
Sorry that suggestion was a little broad, not all Neolamprologus are shelldwellers. A few more popular ones are Lamprologus brevis, L. multifaciatus and L. ocellatus. The multis max out at about 1.5" and are interesting to watch.
 
My tap is at a ridiculous 8.4 after it comes into equilibrium with the atmosphere.. My bettas and platties seem to be just fine.. Biological filter works great as well.
 
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