How can you coagulate dead suspended algae in ground swimming pool?

Flocculant Some of the particles that enter your pool will never sink to the bottom because they are too small and light; they remain suspended in the water indefinitely.

Some examples of this type of particle are bacteria and viruses, broken pieces of pollen, fungal/algae spores and the microscopic dust particles around which raindrops form. Other particles, such as the dead, suspended algae, will eventually hit the bottom.

Although the filter system will eventually remove most suspended particles of this size you can accelerate their removal by using a flocculant.

Different flocculants work in different ways but all encourage the suspended particles to cluster together into 'clumps'. These 'clumps' sink to the bottom of the pool faster. Generally speaking application of a flocculant will clear the water overnight

• Overfill the pool by at least 75-100mm (3-4") to allow for water lost during the Vacuum-to-Waste that follows the flocculation process
• Superchlorinate and adjust the pH as required, then let the pump run for 2 hours
• During this 2 hour period, thoroughly scrub the steps, sides and bottom of the pool with the pool-brush to remove algae and adhering dust/dirt
• Switch the pump to 'Off'
• Mix flocculant with water in a watering can; follow the manufacturers' instructions and don't skimp on quantities. (We routinely use 5 litres of flocculent in a pool of 50 m3).
• Sprinkle the mixture evenly onto the surface of the pool
• Allow the water to remain still for 12 hours or so, until there is a layer of settled sediment on the bottom. Overnight is best.

Note: - Sometimes a whitish, lumpy scum forms on the surface. Skim this off into a bucket. Do not try to remove the scum with a net because it will break up and you will have to wait for another 12 hours for it to sink to the bottom

· Vacuum the sediment to 'Waste'; not through the filter

Note: - The sediment is extremely light, not much heavier than the water, and is easily disturbed, but don't worry if you miss some. You will have to work quickly, because you are pumping the water to waste, but not so quickly that you stir the sediment up too much

· When most of the sediment has been removed by vacuuming, stop the pump and set the Rotary Valve to 'Recirculate'

· Let the pump run for 2 hours. During this period the flocculated particles that escaped the initial vacuum to 'Waste' will congregate in a few places on the bottom of the pool, deposited there by the currents circulating in the pool water.

· Set the Rotary Valve to 'Waste', not to 'Filter', and vacuum the sediment away

· Check and adjust water level, Chlorine and pH. Repeat as and when required.

Note: If your pool goes cloudy frequently it's probable that there is a good reason for it. The most likely cause is that the media within the sand-filter needs to be changed due to age