The purpose of the balacing tank in an overflow swimming pool

The different types of balancing tanks
Balancing tank built
The prefabricated balancing tank


How to calculate the volume of the balancing tank?
- The volume of the pool,
- the nature of the waterfall or perimeter overflow,
- the length of the overflow,
- the expected number of swimmers; this is a question of whether your pool is for strictly private use or whether you expect to have a large number of people in it,
- the flow rate of the filtration pump,
- the presence of an auxiliary pump which improves the overflow effect by increasing the thickness of the water layer.
The accessories necessary for the operation of the balancing tank
- A suction hose between the balancing tank and the pump; that’s obvious but it doesn’t cost anything to say it.
- An overflow to prevent the tank from overflowing in the pump room when there is a large number of swimmers in the pool or when it rains. It is usually connected to the main sewer.
- A non-return valve to prevent the pool from draining by this balancing tank overflow when the pump is stopped. However, if the pump stops when this non-return valve is slightly open, the pool water will return to the balancing tank by gravity and when the water level reaches the tank overflow pipe, the water will flow into the drain. In this way a pool can be siphoned off more or less completely, depending on the level of the overflow.
- A water level control system is crucial; it acts in both cases: lack of water or excess of water in the balancing tank.
- A water inlet equipped with a solenoid valve controlled by the regulation system. The water is topped up automatically according to water losses due to evaporation, splashes from swimmers, etc…
What is the price of a balancing tank
For a prefabricated high density polyethylene balancing tank of 3000 L you need to plan around 1000 €; the same prefabricated concrete tank will cost you only 500€, but you’ll have to pay the transportation. A concrete tank built in the pump room at the same time as the swimming pool will have to be included in the total estimate; the price range is between 2,000 and 2,500 € for the same volume. This price must include the waterproofing of the bottom and walls of the tank. The use of the gutter as balancing tank is a slightly cheaper solution if you agree to leave it open.