As the name suggests, the gravity setup is based on gravity. Due to gravity, water always flows to the place where the water level is lower. This means that by a gravity setup the water flows into the filter when the water level in the filter becomes lower than the water level in the pond. The main characteristic of the gravity setup is that it is build in a way that the water in the pond will be equal to the water level in the filter. For optimal use of the volume of the filter, the pond level should be close to the maximum water level in the filter. When you place the filter and connect it to the pond, it with fill up with water due to gravity. To keep the water circulating, a pump must be placed at the outlet of the filter to get the clean water back to the pond. This will cause the water level in the filter to drop and at the same time the water level in the pond will rise. Then the round starts again with the dirty water flowing into the filter due to gravity.
Something important to know is that the location of the water level sensor depends on which setup you are using. By a gravity setup the water level sensor should be placed downwards in the chamber of the drum, and both floats must be under water. When the filter panel is full of dirt, the water can no longer pass through the panel. This will cause the water level in the chamber of the drum to drop, and the top float will move downwards. The water level sensor detects that the position of this float has changed and the cleaning process will get activated.
Besides the gravity setup, you can also go for the pump fed setup. It’s called a pump fed setup because the water flows into the filter through a pump. The advantage of the pump fed setup is that the water level of the pond does not have to be the same as that of the filter. This means you do not have to place the filter in the ground, even though your pond is completely in the ground. The big difference with the gravity setup is that the dirty water flows from the pond to the filter by a pump. Due to gravity the clean water will flow from the filter back to the pond. With a pump-fed system it is advisable to create a staggered upward arrangement a the outlet using an S-bend. This ensures that the filter is always partly filled with water and you are assured of sufficient water for cleaning/rinsing.
Something important to know is that the location of the water level sensor depends on which setup you are using. By a pump fed setup the water level sensor should be placed upwards in the front chamber of the filter, and both floats must be above the water. When the filter panel is full of dirt, the water can no longer pass through the panel. This will cause the water level in the front chamber to rise, and the bottom float will move upwards. The water level sensor detects that the position of this float has changed and the cleaning process will get activated.