If you mean the water flowing from a filter, yes. It needs to fall into the tank water to work properly.
Nearly all lakes have streams flowing into them and out of them. Many lakes are streams that were dammed to form the lake. The outflow is the water flowing through or over the dam to control the lake level. Source: Riverlorian.com
out flow means that where the water goes example :"the outflow of the river Nile is the Mediterranean sea.
If input flow (inflow) to a water holding area is greater than output flow (outflow), the amount of water held in that area will increase. The water level will rise because more is coming in than is going out. As water level rises, outflow may increase. Or it may not. There are variables. But in the mean time, water is "backing up" in the area under inspection.
You aren't at water level.
Nile River
If the water level of a beach is above sea level, it is called "high tide."
When an underwater wave approaches shallow water, the wave is pushed up above normal water level, and then travels toward land above normal water level.
200 mtrs above see level
Inevitably, there will be some dust and much in the water supply, and the heater should be above this level to ensure it will not overheat.
It is called a syphon tube and water will only flow if the tube is filled with water and the outflow end is lower in height than the water level in the bucket. It works by atmospheric pressure.
Assuming no other complaints you would only need to change water to lower the total dissolved solids level or cyanuric acid level. TDS should be below 500ppm and cyanuric acid ~50 ppm.
Height above sea level