Pre-Pump Strainer(s)

After the balance tank (if there is one) the pool water is pulled under suction into the plant room. In here it must go through a series of various components that will always occur in the same order:

  1. Pre-pump strainers(s)
  2. Pump(s)
  3. Filter(s)
  4. Heat exchanger

The pre-pump strainer is designed to trap the larger items of physical pollution before they can get into the pump itself, where it would cause damage. The strainer basket sits inside a vessel and can be removed for cleaning. They will need to be cleaned out regularly in order to prevent them becoming completely blocked with debris. Here is an example of a pre-pump strainer that has been allowed to accumulate too much debris. The pre-pump strainer is a separate component to the pump on large systems, but on smaller systems it is usually an integral component of the pump.


Both types (separate and integrated) have lids which can be removed in order to take the strainer basket out for cleaning. The integrated type usually can a lid that is see-though and can be turned anti-clockwise on a thread. The strainer vessels that are separate to the pump usually have more robust lids that bolted down onto the strainer vessel. Care must be taken when replacing the lids after having had the strainer vessel open as it can often be the case that the rubber O-ring that forms an airtight seal between the lid and the strainer vessel can be misaligned when replacing the lids and therefore wont form a good, airtight seal and will start to suck air into the circulation system when the circulation pumps are turned on.

Instead of attempting to clean the strainer baskets when they are wet, have enough of them in the plant room so that you can rotate them. When it’s time to clean the strainer baskets, take out the dirty one and replace it with the clean one that you have already cleaned. Then leave the dirty strainer basket in a safe place to dry out and then remove the debris and repeat the process the next time.                           

Circulation Pumps

The circulation pumps are the ‘heart’ of the circulation system. They are designed to continuously pumps water around the system at a pre-determined rate called the flow rate. In larger installations there are usually several pumps working at the same time, with additional pump(s) on standby. In smaller installations, there may only be one single pump.

They work by having an impeller (which is similar to a propeller), which is housed within the pump casing and is connected to an electric motor, which rotates it at high speed. This causes water to be sucked into the pump on the suction side and forced out of the pump on the delivery side.

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