Did you notice them before adding water? Are they actually even attached to the tank, or are they just stuck in the corner?
I'd baste them or point some flow at them and see if they go away - especially before agitation and biofilm, bubbles just stick to the corners and sides more than a fully operational tank, and those don't look like they're actually part of the acrylic work at all to me.
I'd baste them or point some flow at them and see if they go away - especially before agitation and biofilm, bubbles just stick to the corners and sides more than a fully operational tank, and those don't look like they're actually part of the acrylic work at all to me.