What size is your Betta's tank Blue?The thing with Snails and Betta's is that the majority of the time,Betta's do not care to share their space with them.
I also have to say that I have alot of snails,both Brig's and Cana's,and Algae is usually their last choice in the food department.They'll eat that if there's not any thing else.Depending on your tank size,you may want to look into Oto's or maybe a Bristlenose.