Hi - I have a quesiton about sunscreen in foundations - I'm currently using Neutrogena Visibly Even foundation, which has a SPF 20 that's titanium dioxide, so it's good for UVA - is this enough, or should I be wearing a sunscreen underneath? I usually wear a moisturizer underneath - I just bought Aveeno Ultra-Calming moisturizing cream and was wondering if I could get away with that and then foundation on top, or should I buy the lotion with SPF for day?

Thanks!

Beth