Hello there and welcome to the forum. I have answered your posts in the betta section already so feel like I already know you and your sister told me about getting you the betta. I think you two will have a lot of fun together with your fish.
30 gallons is quite a home for your betta, cardinals and cories. It sounds like a lovely tank and Kayla can help you post some pictures later when you get comfortable here.
Thank you and Kayla for you joining us and we will try to help you with anything that comes up but hopefully we can keep too many problems from happening to begin with.
Welcome and have a good time here.
Rose
P.S. my goodness Jim that is a large order to fill but thanks for the lovely compliment!
