I have recently designed and had fabricated the following two sumps for my Aquarium (See image).
I have a pump in the right hand container (section 4), and the return is coming back into the left hand container (section 1) - both flowing at equal rate (~1000lp/h).
Two 32mm flexi-pipes connect the two containers.
I was expecting the water level in both containers to equalise, but the left container is consistently running near to maximum whilst the right container water level is - as I would expect it to be - at the baffle height for 'section 1'.
Why am I not seeing equal water heights in both?
See below a picture of the situation occurring with RED lines indicating water height, BLUE lines indicating baffle heights, GREEN arrows indicating water flow direction. Please ignore the fact that I currently have one of my bypass valves turned on - it's all I can do to drop the water height in the left container a few centimetres.
Note - Reducing flow rate, and removing water from the system does not seem to have any positive effect on the left hand container. Filter sponges/socks etc were added after this effect was happening. The system has been running stable for 24 hours with this effect visible.