They look like BG or HBG to me, but it's hard to tell. You said there are "thousands"? There wasn't much in the vid or photos for scale, but they appeared large for a 6" HSB to control...did you find any larger HSB to stock when the water cools off?

I know you don't want LMB.... but they do a pretty good job.

"Forget pounds and ounces, I'm figuring displacement!"

If we accept that: MBG(+)FGSF(=)HBG(F1)
And we surmise that: BG(>)HBG(F1) while GSF(<)HBG(F1)
Would it hold true that: HBG(F1)(+)AM500(x)q.d.(=)1.5lbGRWT?
PB answer: It depends.