Yo Wann
Sounds like you have some FA issues - could this due to a lack of rooted vegetation established as it's a new pond? If you get some beneficial vegetation going it will help tie up those nutrients and help prevent FA from flourishing.
I think HBG are a great companion species for your SMB/HSB fishery and they will not become an issue you can't manage through angling and trapping if necessary. I think the fish that make it through the gauntlet will be trophies and a ton of fun to catch.
Good to hear from you, been a while. Viva El Wann!