They are flow monitors. It can detect gph going through pipe and text if reduced. The return pumps are apex cor20.
The first chamber where water comes in will have macro algae. 2nd chamber for skimmer, 3rd live rock and last one for return pumps, auto top off, and heaters. I think per Rick’s suggestion for Ohio Reef I will have an open house before I open for those that want a behind the scene tour