Glowlight tetras!!!! Get them!!! I absolutely adore my glowlights. You can see one in Pitluv's 2nd picture - the fish with the orange stripe. I admit, they don't seem like much to look at, at first. But when they school, it's magical! They also have the smallest bioload of all tetras, so you can get a good number of them.
As for the water - my water has a very high PH and is very hard. They do fine. Most store bought fish can adapt to a variety of water types.
My pH is 7.6, all the types I own are doing great in it.
BUT as I said in my first post, Glowlights are very shy timid fish. But yes, they are gorgeous! I have 3 here, I wish I could get more :(
The inch a gallon rule is a loose guideline, I actually don't use it much. And I have some aquarium books written by longtime hobbyists that have stocking options some 1 inch per gallon people would freak out at. But when you stop and think about it, a lot more goes into stocking than just space.
Temperament: aggressive fish need more space to be away from other fish.
Bioload: herbivores and omnivores have a smaller bioload than carnivores.
Schooling: schooling fish need big groups but comparatively little space because they stay together, not spread out like non-schoolers.
All that said, 6-7 black neons, 1 male betta, and 2-3 ghost shrimp sounds perfect.