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.
You aren't at water level.
The water level can change dramatically depending on various factors such as tides, rainfall, inflow/outflow rates, and environmental conditions. In some cases, it can fluctuate by several meters or more within a short timeframe.
Nile River
The water level of the lake will remain stable because the rate at which water is leaving the lake equals the rate at which water is entering it. This creates a balance in the water level despite the continuous inflow and outflow processes.
200 mtrs above see level
Surface outflow refers to the movement of water from land surfaces into rivers, lakes, or oceans, often occurring after precipitation events such as rain or snowmelt. It is a key component of the water cycle, contributing to the redistribution of water across the landscape. This outflow helps manage water levels in bodies of water and supports various ecosystems, while also influencing soil moisture and groundwater recharge.
To raise the water level in the beaker, you should add more water to it. The amount of water added should be equal to the volume you want the water level to increase by.
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
At 1800 meters above sea level, the boiling point of water is around 93.5°C due to the lower atmospheric pressure.