If you want a "guppy factory" you could do what I did.
For your "factory", you need a filter, and put pantyhose or nylon fabric over the intake.
Buy 3 female guppies and 1 male, and plant the tank if possible. (as many "bushy" plants as you can- anarchis, hornwort,mosses, and water wisteria all are excellent for this.)
Then ignore them. Feed'em, do w/c's, but don't move them. IF there are hiding places, you will probably have 5 fry in a month.
Giv'em time to grow up.
Then, only feed your turtle males. You only need, realistically, 1 male per 5-10 females.
With 1 male and 5-8 females, you'll be producing about 40 fry a month, and in the right planted setup, most will survive.
I think it's better to let nature do its thing, and give it the opportunity, than use breeder boxes to save EVERY fry. There are inevitably some runts, some weak, perhaps some sick fry born- and you don't really want them to survive, even for the turtle.