Thanks guys. While I agree that knowing the on’yomi may be useful in the future, I’m having a lot of trouble with it now for the same reason Joel suggests. I can’t remember it because I can’t attribute it to a meaning.
So, I’m going to edit the cards to include both, and try and remember the on’yomi as well while I do them, but I won’t focus as hard on it unless there’s some vocab that I need to remember it for.