I have yet to find a way to keep my biowheels working right after a rather short time. When they are first set up the water returning to the tank easily rotates the wheels but in no time at all, let's say 4 months, the wheel either stops moving or requires very frequent maintenance to keep working. I have several that I treat as if the wheel simply did not work. That means that the cartridge is my main biological filter in those tanks and I take no credit for the wheel. I love the idea of a biowheel but it is not well executed in a real world practical filter. If you get a bad overflow back along side the inlet path in less than a day, or even less than a week, you are being too gentle when rinsing your cartridges. When I clean a cartridge on my tanks it gets a good cleaning and that means I do not see "overflow" water flow in less than 2 weeks or even more.
A side note on stocking: 2 orandas in a 14 gallon is grossly overstocked, even without the molly. Each fancy goldfish needs about a 20 gallon for the first fish and an added 10 gallons for the next. That puts you at 30 gallons plus another 3 or 4 gallons for the molly. This is not an issue with your filter but will greatly affect how often you must do huge water changes. Instead of the typical weekly 30% water change, you will be facing that big a change every 2 to 3 days. Please rehome your fish or get a much larger tank.
