[slief]

Originally Posted by h3dgehog

Noticed that in Klaus' picture of one of the first vlies step sumps that the user placed two foam/sponge blocked by the return pump. I can only guess that this is because of micro bubbles from the skimmer being taken into the return pump and back to the display.

Can someone comment on whether this is a problem that is expected? Any updated from the user on whether the micro bubbles are still a problem?

Micro bubbles should not be an issue. Note that the skimmers effluent is located at the opposite side if the sump from the return intake so any micro bubbles should rise to the surface long before making it to the return pump, plus a properly sized and properly tuned skimmer should release very little if any micro bubbles as the proteins in the water cause the bubbles to stick together and rise to the neck of the skimmer. If there isn’t a proper load in the tank, then there won’t be sufficient proteins/dissolved organics to bind all the bubbles in which case there may be some micro bubbles but again, they should rise to the surface before making it around the skimmer, across the wall where the fleece compartment is to the opposite side of the sump where the return intake is More likely the person put the sponge filter in there to seed the tank with bacteria or add additional biological surfaces there.