System is actually quite simple.
4 tanks in parallel...
All drain via overflows (basically the twin 3/4" bulkheads at the top of each aquarium are just simple overflows)
The effluent lands in 2 x 4" 400micron coarse mesh socks (just big enough to catch large debris, fish, shrimp)
The effluent then passes horizontally through three grades of 2" poret foam (6 pieces).
Treated water passes from chamber 1 to chamber 2.
Submerged sump pump picks up water and sends it down a 3/4" line.
Water has 3 parallel paths.
1. through the UV Filter (25W) or 2. through the CO2 Reactor or 3. through a Flow Meter (exist just to register that water is actually moving.. a simple Flow Switch could do the same).
Water comes backtogether into one 3/4" line... Travels down a trunk and then goes off to 4 parallel paths (each leading to one of the display tanks).
I never see any bio-film in the sump, so it doesn't slough off of the 3/4" effluent lines. I only see it in the display tanks.... Tanks.
My system seems complicated... however, if it were four standalone tanks there would be:
3 more pumps, 3 more discharge solenoid valves, 3 more CO2 reactors, 3 more UV filters, 3 more surface skimmers, 3 more Sumps, 3 more auto-top arrangements.
I'm glad to hear you get it on the hoses. It might be the intial seed bacteria that was added to the water column in the sump to promote colony growth in the poret foam. Perhaps some colonizing bacteria has taken hold in the lines as well.
The cut outs seem to happen about 2 to 3 times every 24 hours (I record the number of times the relay has cut out... I see when it happens on a little graph). There is a combined 16' feet of line from the Sump Pump to the Display. Overall, the system has 5' of head.. .so that's allot of back pressure. I think the check valve is my best bet to cut back on the bio-film getting back flushed and then shot out.