Thanks for the help, I'm more confident about the process now.
The filter is an integrated Fluval filter in a Fluval Accent tank. As for ammonia source, I hoped to find something at the pet store. Is there a product in particular I should look for, or just any pure ammonia product?
We have a Petco and Pets Plus. The Pets Plus had pure ammonia products for aquariums, the ones I remember looked like black power or pellets in plastic jars I think.
I do want my Cory catfish to have a school of six, and the Danio at least five-eight max, but the Petco only has two or three Long Fin Blue Danio right now. So, I hope they get more in. Same with the Albino Cory catfish, I've never seen enough there for a full school. The last time I went they only had one Albino Cory.
In a 25 gal, is it possible to have a school of six Cory Catfish, and two schools of two species of Danio? If each school of Danio is the minimum size, five, that would be sixteen fish in all counting the Cory.