Usual stuff – Reduce your light duration or intensity, test your water regularly and try to balance it, more water changes to reduce nitrates, run CO2, treat with peroxide for immediate removal, develop a regimented macro/micro nutrient plan, feed the fish less, use filter floss or Purigen in your filter solution, introduce faster growing plants and floaters, they usually nutrient hogs…I’d start with this list.
Tasty-Ad3766 
Usual stuff – Reduce your light duration or intensity, test your water regularly and try to balance it, more water changes to reduce nitrates, run CO2, treat with peroxide for immediate removal, develop a regimented macro/micro nutrient plan, feed the fish less, use filter floss or Purigen in your filter solution, introduce faster growing plants and floaters, they usually nutrient hogs…I’d start with this list.
don’t know if you can pair them with betta but my Mollies do a good job of cleaning algea from plants