3 years ago I developed a system for filling inverted aquariums by applying a vacuum to a "schreider" non-return valve adapted to fit on the aquarium.
I was looking for a supplier of extruded clear plastic tube to produce a commercially available system for aquarists.
"Thanks" to a gentleman in Singapore using the principle I developed to manufacture inverted aquariums, a tremendous interest has been generated world-wide. The problem is, despite my explaining in detail how to build this system, people not associated with the refrigeration/air conditioning industry don't understand how to make the vacuum.
I need some feed back. If someone phoned you with a request to "vac their aquarium", what would you charge?
Your main consideration is to stop the vacuum before the water is drawn into the pump.
Now If you want to see this system in operation, go to "youtube" "The Romaurie-Effect" for video clips of this and Mr. Ho's "Fishfreedom" aquariums.
Romaurie.