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Wilo pool pumps: how to choose a pump for pool filtration and draining
A pump is the heart of every swimming pool. It ensures water circulation, supports filtration and has a decisive influence on how clean and crystal-clear the water remains throughout the season. In this article, we explain how pool pumps work, how to size them, and the differences between the two types you will appreciate most around the pool: a self-priming filtration pump and a submersible drainage pump for emptying the pool.
Author: Jaromír Bittner - Sales Representative
Two tasks, two types of pump
With a domestic swimming pool, you are essentially dealing with two different things. The first is daily circulation and filtration – the water must circulate continuously between the pool and the filtration unit so that impurities are captured and pool chemicals are distributed evenly. The second task is draining and maintenance – pumping out water before winterisation, during water replacement, or lowering the water level after heavy rain.
Each of these tasks requires a different design. Filtration is handled by a surface-mounted (self-priming) pump, which continuously pushes water through a sand or cartridge filter. Draining, on the other hand, is best handled by a submersible drainage pump, which is placed directly on the bottom and pumps the water out almost completely. Wilo offers proven solutions for both roles – the Initial POOL range and the Wilo-Drain TMW submersible pump.
Wilo Initial POOL filtration pump
The Initial POOL range consists of self-priming pool pumps designed for reliable water circulation and filtration in small private swimming pools up to approximately 50 m³ in volume. Water is drawn in through an integrated washable strainer basket, which captures coarse debris (leaves, hair, insects) before it reaches the impeller and filter.
The pump is self-priming – it can draw water from a suction lift of up to 8 m, so it does not need to be installed below the pool water level. It is driven by a single-phase asynchronous two-pole 230 V / 50 Hz motor with IPX5 protection and insulation class F. The hydraulic section is designed for contact with clean and chlorinated water up to 35 °C.
Materials used
The service life of a pool pump depends above all on the resistance of its materials to chlorinated water. Initial POOL uses a pump casing and strainer basket made of Moplen (polypropylene), an impeller made of Noryl, an aluminium motor housing, and a mechanical seal made of silicon carbide and NBR (nitrile rubber), which prevents water leakage even during long-term operation.
Two performance levels
The range is supplied in two versions, differing in motor output and therefore in flow rate and head:
| Parameter | Initial POOL 500 HP | Initial POOL 750 HP |
|---|---|---|
| Product code | 2865191 | 2865192 |
| Rated motor output | 0.37 kW (0.5 HP) | 0.55 kW (0.75 HP) |
| Rated current | 3.2 A | 3.7 A |
| Max. flow rate (Qmax) | 15 m³/h | 18 m³/h |
| Max. head (Hmax) | 11 m | 13 m |
| Suction lift | up to 8 m | up to 8 m |
| Power supply | 230 V / 50 Hz, single-phase | 230 V / 50 Hz, single-phase |
| Connection (suction and discharge) | 6/4" (1½") | 6/4" (1½") |
| Protection / insulation class | IPX5 / F | IPX5 / F |
| Max. water temperature | 35 °C | 35 °C |
The smaller Initial POOL 500 HP is suitable for smaller pools and shorter pipe runs. The more powerful Initial POOL 750 HP is recommended for larger volumes or where the filtration unit is further from the pool and the pipework creates greater resistance – its higher head of 13 m copes better with longer runs.
Wilo-Drain TMW submersible pump for draining
Not every pool needs to be completely emptied at the end of the season, but with above-ground pools without fixed filtration, in cases of heavy contamination, or before deep cleaning and repairs, it is often unavoidable. Pumping out thousands of litres with a bucket is no fun – which is why a submersible drainage pump such as the Wilo-Drain TMW 32/11HD (code 4048715) is so useful.
This is a robust submersible pump that you place directly on the bottom of the pool or sump. Thanks to its open multi-channel impeller with a 10 mm free passage, it can also handle water containing small impurities. The pump housing is made of glass-fibre-reinforced polypropylene (PP-GF30), while the shaft and motor are stainless steel – a combination that also stands up well to chlorinated water.
| Parameter | Wilo-Drain TMW 32/11HD |
|---|---|
| Rated motor output (P₂) | 0.55 kW |
| Power input (P₁ max) | 0.75 kW |
| Power supply | 230 V / 50 Hz |
| Protection rating | IP68 |
| Free passage through impeller | 10 mm |
| Max. immersion depth | 3 m |
| Max. medium temperature | 35 °C (up to 90 °C for short periods) |
| Discharge connection | G 1¼ |
| Float switch | yes (automatic operation) |
| Power cable | 10 m, with Schuko plug |
Use in practice
The pump is ready for immediate use – thanks to the float switch, it switches on and off automatically according to the water level, so there is no risk of dry running. When draining a pool, place it at the deepest point, connect the shortest and straightest hose possible (a narrower or longer hose increases resistance and reduces performance), and discharge the water into the sewer or a soakaway in accordance with local regulations. Any remaining thin layer of water on the bottom can then be wiped up or removed with a wet vacuum.
Away from the pool, the pump becomes a versatile helper – it can be used for emptying barrels and rainwater tanks, cleaning garden ponds (note that particles larger than 10 mm could clog it), and pumping out water after torrential rain.
What to watch out for during installation and operation
Always connect the pump to a socket protected by a residual current device (RCD) – water and electricity are a dangerous combination. Place the filtration pump on a stable, level and low-noise base; correct installation significantly reduces the transmission of vibration and noise. Check the strainer basket and filter ideally once a week – a clogged filter reduces flow rate and efficiency and increases energy consumption. Before winter, drain the pump, clean it and store it in a dry place protected from frost. We also recommend entrusting installation and any repairs to a qualified installer.
Frequently asked questions (FAQ)
For daily circulation and connection to a filtration system, a surface-mounted self-priming pump such as the Wilo Initial POOL is ideal. It ensures water circulation between the pool and the filter and helps keep the water clean and crystal-clear.
For quick draining, lowering the water level or pumping out residual water, a submersible drainage pump such as the Wilo-Drain TMW is suitable. It is useful for cleaning, water replacement and winterisation.
Not every pump can withstand permanent contact with chlorinated water. Choose models designed for chlorinated water with suitable material construction – they have a longer service life and better corrosion resistance.
The Initial POOL range is intended for small private pools up to approximately 50 m³ in volume. For larger volumes or longer pipe runs, choose the more powerful 750 HP version with higher head.
The water should pass through the filtration system at least once a day, ideally twice. The exact time depends on the pool volume, pump performance, water temperature and intensity of use.
Modern pumps are designed for quiet and economical operation. Noise can be reduced further by mounting the pump on a stable base and carrying out regular maintenance.
Ideally once a week, or more often if contamination is heavier. A clean basket and filter mean higher performance and lower energy consumption.
Before winter, drain it, clean it and store it in a dry place protected from frost. This will extend its service life.
