Read
I Heart Recruitment and you'll cringe every time someone says "quality over quantity" too.
Obviously, no chapter should have ovaries as the sole requirement for membership, but the point is that increasing the size of the pool of PNMs will no doubt increase the quality of new members. Quantity drives quality, so you can have both.
ETA: Sorry to sound obnoxious for always plugging this book, I swear I don't work for Phired Up. I truly think every sorority woman should read it.