Hey there, welcome...
but time out....
You're putting 3 bettas together?? I hope 2 are female, or you're going to be watching one mean fish fight. If you have a green one, my moneys on him.
Even with 1male/2female, 88 gallons will require decent filtration, meaning more power, and likely leading to more water movement/current. No good a betta. Also, if it's a tall tank, you better hope the betta likes going to the top for food, because he may never find it otherwise. Some stay in and about the plants all day, only going up for air.