Main Return - If the valve is left fully open the syphon effect will empty the weir too quickly, the water comming over the weir will splash and gurgle as it drops through the void (lots of noise!). Slowly close down the valve until the water rises in the weir and just ‘trickles’ down the Balanced Return pipe. It takes a little time to balance.
Once done - No trickle noise from the weir and no gurgling - Silence!
(Tip: Do not use strainers on either of the Weir pipes. From experience - they always clog! I capture detritus at the sump end, using coarse foam and filter floss. A filter sock would work just as well.)
(Tip: Do have unions on either side of the valve so you can take it out for annual cleaning.)
Balance Return – This is left just above the Sump water level so you can see the amount of flow (trickle) as you adjust the valve. Once set. I add a short length of pipe to extend this to just below the water level, stopping any trickle noise at the sump end. The curve at the top, stops any noise from the trickle of water at the tank end.
Valve – Best option is a Gate Valve, as it enables finer balancing. A Union Ball Valve could also be used, but not the cheaper straight ball valves as they are more difficult to fine tune. Fit the valve as near to the end of the return pipe as possible, and easily accessible.
Pumps & Piping - I run two Jecod DCP 8000 DC feed pumps, each one moving c.6000 litres per hour (c.1,580 UK gph).
Two 25mm UPVC pipes, with two outlets each, feed the display tank. One 40mm Main Return pipe, One 40mm Balance Return pipe & One 40mm Gate Valve. With a 6.5 meter horizontal run between the Display Tank and the Sump.
Weir - I use a High Capacity Weir Comb (not essential for silent operation) and have a glass cover over the weir to stop fish & critters entering.
Do make absolutely sure you have sufficient capacity in your sump for when the pump is turned off, as the the water from the weir and the top of the display tank, flows back to the sump. Do use a cover over the weir box to stop critters entering and being 'wizzed' to the sump. Do not add 'one way' valves to the system. In my experience, they constrict water flow and regularly fail!
System originally installed 2016. No issues experienced at all, to date. Annual maintenance only.
A good article for more information can be found here at : 'gamcreef.com'.