I use about 10-12 hanging breeder nets in my fish room right now. It is a pain, having to drop them down when doing water changes over 50%. For my main fry tank, where I have 5 breeder nets hanging, I use a 15 gallon. Since it is shorter than a 20H, you can remove more water volume without the nets going dry.
My Malawi fry typically spend the first 2-3 months in a net breeder before moving them to a 10 or 20H. I like having better control over feedings - which the smaller volume of the enclosure affords.