Last nite test the overflow after filled up both main tank and sump.
Meet with some problem
Overflow was too slow even after I tune down my Atman AT 104 pump
Check every part of the overflow .Cannot find any problem
Work till 0430 am.
Very tire retire for the day
Check your PO4.
Make sure it is below 0.03 ppm
Remove those rock with red slime and brush
out the red slime.
Rush with your tank water before put the rock
back into the tank.