Planted Tank Guru
Join Date: Sep 2006
Location: Northern California
Strong powerhead forcing water through it. The direction of the water flow (against the side of the tube; see last picture) rather than having it go straight down causes a vortex effect.
1000-1200 bubbles per minute? That's a lot. Assuming 10 bubbles = 1mL, You're gonna get 100 mL to 120 mL of dissolution per minute? Hrmm.