Most people know that they should look after the

It stands to reason that if you are to maintain a sparkling swimming pool, you will not only need to chlorinate the water regularly and follow a sensible maintenance program, you will also have to care for the 'heart' of your pool. All pools need an adequate pump and filter system to keep the water clean and healthy. If you are a new pool-owner or thinking of replacing your existing pool pump, read on. A good pool-builder will advise new pool-owners on the best type and size of pump, filter and motor for their pool. It is absolutely essential that the filter is the correct size for the pool and equally important that the pump (which delivers water to the filter) and motor (which drives the pump) are matched to the filter size. All too often pool-owners opt for smaller filters simply to save money, without realizing that this will result in an under-filtered pool. If the filter cannot handle the water pumped into it, it will not adequately remove dirt and debris from the water. All the water in a swimming pool needs to pass through the filter at least twice every 24 hours. For example, for a 50 000-litre pool, 100 000 litres of water needs to be filtered every 24 hours. This means at least 12 hours filtration for the average domestic swimming pool. Nowadays most pool-builders opt for sand filters, which are easy to operate and some of which incorporate pressure gauges that will help you ascertain if the equipment is working properly. If the reading is higher than it should be, the filter probably needs to be thoroughly cleaned; if it is too low, you may have a leak or a blockage in the suction line. There may also be too little sand in the filter. Remember, too, that if the filter is too small for the pool, the filter will clog up quickly and more frequent backwashing will be required - an unnecessarily time-consuming factor. Most filters should be backwashed when the pool-owner notices that the automatic pool cleaner has become sluggish. In the normal operation of the filter, set the valve on 'filter'. Set to 'backwash' when you need to clean it. Run the motor until the water in the sight glass is clear, then switch to 'rinse' to settle the sand bed in the filter. Then reset to the 'filter' setting. When cleaning the pump basket, set the valve to 'closed', and if you experience difficulty priming the pump, turn it to 'circulate' on start-up. Just remember to take the valve out of the 'closed' position before restarting the pump or you could damage it. If the pump still will not prime, or if it loses its prime while running, check the pipe leading to it and the lid seating. Alternatively, the strainer basket or suction pipe could be blocked or the water level may simply be below the skimmer opening. Top up and try again. Modern self-priming pumps have a long life, if properly cared for. Ensure that the pump lid is sound and that the 0-ring does not perish. A damaged 0-ring will cause the pump to draw air and if the lid is worn, air will enter the pump and interfere with the operation. When water leaks out between the pump and motor, the problem is often a burned-out seal. If you are not sure how to replace it, contact your supplier.