In my opinion, cardinals are not the best choice for a beginner with really basic, hard and alkaline water. They are kind of sensitive, and they prefer softer water. There are many hardier tetras you could choose that would tolerate hard water better than cardinals. For example, black skirt tetras, Xray tetras, black neon tetras...I have found all of these to be more hardy. Also, cardinals are about $3-$4 a fish regular price. So, you can do what you'd like of course, but if you're asking for opinions, I don't think cardinals are the best choice.