EV-240 in action (test run).
Before that test run for 2 days and no foam produced.
Thought pump not strong. Using Ocean free 9000 (4500 l/h flow rate) which is actually the SEN 900 recommended by aquaC.
This evening troubleshoot and found the water inject choked by 2 pcs of silicon, ~!@#$%^&*().
After removing them, here's the foam I got. Phew what a great difference.
The water returning back to the sump is ultra noise like water fall, have to find some ways to solve it.