Hi,
I would be very wary of the guppies, guppies will nip bettas and bettas will attack guppies mistaking them for other males.
I would also rehome the algae eater asap as they are aggressive, and will grow far too large for your tank. Its better to get rid before it gets to that stage.
Hopefully your betta will be okay for now, but keep a close eye for any signs of bullying or nipping going on, and remove him if this happens.
Laura