Julian -
Congrats on the new 45g Bowfront! That is cool platform for a tank setup.
I'm happy you want to keep cichlids.... however, you need to differentiate between a New World Cichlids (South American) and and Old World Cichlids (African). Unfortunately, they cannot be kept in the same tank.
Before I go into detail. Do you want a tank with a lot of smaller, active, and territorial fish?
OR
Do you want a tank with ONE, TWO, OR MAYBE THREE large fish that are the focus of the tank?
Don't worry too much about PH right now. Do you have a cycled tank to pull media from? Cichlids, both African and South American are hardy fish, but they need a good start just like any other fish. If you have not read this yet, please do:
http/www.fishforums.net/index.php?/topic/421488-cycling-your-new-fresh-water-tank-read-this-first/
If you already are familiar with cycling, please pass that.
I've kept many new world cichlids.... lots of experience and what can and cannot go together (for the most part you need to know what you are doing to combine them, and even then they are unpredictable). And old world cichlid tank is going to be more of a sure-fire "community" with problems.
Once you have decided on one or the other... let me know and I can recommend stocking suggestions for a 45g.... although you are going to be very limited with new world cichlids if you want larger fish. Just know "electric yellow an electric blue cichlids, a few convicts an some kribensis cichlids" WILL NOT WORK.