I live in Cincinnati. Local Water 8.4ph 14gh 4kh aged from the tap.
I have two tanks that seem to be doing fine. ]

Tank 1 is 38 gal 7.3ph 3kh. It is planted, contains aged drift wood.
Filtered with two whisper power filters and a UGF powered by two
powerheads. Stocked with a 9" black ghost, 9" pleco, and two 3"
gouramis. I've had these fish about three or four years.

Tank2 is 29 gal 7.4ph 3 kh. It is planted, contains less aged drift
wood. Filtered with a whisper power filter and a large sponge with
powerhead. Stocked originally with three black mollies which have
turned into about 30 mollies and population rapidly rising!

For the past couple of months, I've been doing approx 20% water changes
twice per week. Previously, I'd been worried about the high PH of the
tap water so did fewer water changes. But I've read that fresh water
is better than perfect water. And the fish seem to love the water
changes.

What do you think of adding four Angel fish to Tank 1? The current
Tank 1 inhabitants, while very cool fish, are all shy or nocturnal.
I'd like some fish that would be easily seen in the day. However, I'm
concerned that in this relatively small space the fish would be crowded
by the time everyone keeps growing.

If Angels aren't a good choice, what else? I once tried tetras with
a black ghost based on a books statement about the ghost being so
peaceful. Ha ! Tetras came up dead or missing eye balls.