What should the PH level be for tetras in an aquarium?

The tetras would probably like a pH of 6.8 but with the other species you have a pH of 7.0 will be ok  more

I had some black tetras and a few other fish in a PH of around 7.2-7.5 and they did great. but i had to get rid of them due to lack of space with my angelfish breeding. hope i help.  more