The purpose of the pump is to push water through your equipment, circulate chemicals and operate other equipment such as cleaners/water features. They are one of the most expensive household appliances to run, however, they are an absolute necessity.
There are three types, Single Speed Pumps, Variable Speed Pumps and Booster Pumps. They will vary in dimensions and power depending on the pool volume/what you'll be using it for. To keep the pool looking good, you will require at least one pump with a basket to circulate water through your filter (for clarity) and your chlorinator (to stop bacteria).
This pump needs to be matched in flow rate with your filter. You also need to take into account the distance between the pump and the body of water, this is known as "head". The basket will need to be cleaned on a regular basis as it's the final safety net between the water and the rest of your equipment.
A normal pump will pull 280 litres of water through it per minute (based on a 50,000L pool with an average head of 8m and standard 40mm pipe). This pump will circulate the full body of water in just under three hours. For optimal water clarity, this needs to occur twice a day during winter (six hours) and a little longer over summer (eight hours).
A good unit will last you roughly 8-10 years. Over the course of its life, a number of common issues may become apparent. The five most common are:
-
Blocked Impeller
- Symptoms: Deep grinding noise, low filter pressure,
- Repair: Open pump and remove debris caught in the impeller.
-
Faulty Capacitor
- Symptoms: Faint buzzing noise, pump cutting out,
- Repair: open housing and replace capacitor.
-
Worn Down Mechanical Seal
- Symptoms: Whining noise, puddle under seal,
- Repair: Open pump and replace the seal.
-
Air Leak From Worn O-Ring
- Symptoms: Pump losing prime, leak around the lid,
- Repair: Take lid off and replace O-Ring.
-
Air Leak From Split Union
- Symptoms: Pump losing prime, leak around the union,
- Repair: Put on a new union.
If a pump is losing prime (water doesn't fill the wet end basket), you can manually prime it by turning off the pump, closing any necessary valves, taking the lid off and filling it with water until it's overflowing (may take 5-6 buckets). If it is still losing prime, you may have a leak. Leaks that you cannot see suggest that the problem is underground, requiring a leak detection service.
There is another type of pump without a basket, known as the booster pump. It is installed for a number of reasons:
- Operate a pressure cleaner,
- Enable a water feature,
- Push water to the roof for solar heating.
They usually aren't as powerful as your main pump and you need a secondary return line plumbed in to operate one of these units as they cannot be installed on your suction line, the second return line exists in most pool setups.
Below is a comparison of single speed vs variable speed pumps. Essentially, variable speed pumps have another electrical component attached to it which can control the speed of water flow.
Most pool owners will run their variable speed pump for a little longer (12 hours+) at a much lower speed. This unit will typically pay for itself after 2-3 years of use. It's important to note that suction cleaners will not work anywhere near as well at the lower speed. Variable speed pumps are often accompanied by a robotic pool cleaner.
Furthermore, at lower speeds, filtration is better as the same areas of the pool are usually recirculated with a single speed pump due to the pulling force.
