Ideally, the water in your pool should be at the correct pH of 7.4, contain sufficient chlorine to prevent an attack of algae and look as clear as gin. Sometimes though, no matter how long you filter the water for, there remains a degree of cloudiness or opacity that you just can't remove.
If this is the case with your pool, it is probably time to change the sand within the sand-filter as the sand will have lost it's sharp edges and therefore be less efficient than it was when it was new. Lower efficiency in the filter means that the very tiniest particles cannot be captured, and are returned to the pool via the jets. Before you undertake the backbreaking, filthy job of renewing the sand there is something you can do to clear the water swiftly (if temporarily), - apply a flocculant.
Flocculants are generally liquid or granular, and work by imparting an electrostatic charge to the suspended particles. This charge turns the particles into 'micro-magnets', which are attracted towards each other. The particles clump together, become collectively heavier and therefore sink to the bottom faster. Once the particles are on the bottom, you can deal with them and remove them from your pool. (Flocculants are used to clarify beer and some wines, they are safe in your pool and you can swim as soon as you have finished the process outlined below).
Method -
1. Overfill the pool by at 75mm (3") to allow for water lost during the vacuuming process.
2. Superchlorinate the water and
adjust the pH as required, let the pump run for 2 hours.
3. Thoroughly scrub the tiles with the pool-brush to remove algae and adhering dust/dirt.
4. Switch the pump to 'Off'.
5. Mix flocculant with water in a watering can, in accordance with the makers' instructions. (Normally about 500ml in a 5 litre watering can per 10 cubic metres of pool water, but quantities vary with each manufacturer.)
6. Sprinkle the mixture evenly onto the surface of the pool.
7. Allow the water to remain still for 12 hours or so (overnight is best), until there is a layer of settled sediment on the bottom, resembling soggy rice crispies. Sometimes, depending on the type of flocculant used, how much dissolved CO2 is in your pool and what the flocculated particles consist of, soggy white lumps may float to the surface. The lumps will break up if you try to net them, so gently skim these off into a bucket before beginning the vacuum-to-waste procedure.
8. Vacuum the sediment to 'WASTE', not through the sand-filter. The sediment is very light and easily disturbed but don't worry if you miss a little.
9. When the majority of the sediment has been removed by vacuuming, set the Rotary Valve to 'CIRCULATE' and let the pump run for 2 hours. During this period most of the flocculated particles that were missed during the initial vacuum to waste will naturally congregate in several places on the bottom of the pool due to the circulation currents.
10. Vacuum the accumulated sediment to 'WASTE', not through the sand-filter.
11. Return all valves to their normal positions and check/adjust water level, chlorine and pH.
12. Repeat as and when required.

Flocculant can also be applied, with similar swift results, when you have scrubbed a pool that has gone green, or if you have filled your pool with water from a well or canal and want to clear it quickly.
If the above sounds a bit more than you want to take on, we'll gladly come and do it for you! Send an email to newsletter@deep-blue-pools.com to receive our free monthly Newsletter containing Seasonal Pool Advice, Top Tips and details of Special Offers on pool equipment and chemicals

Deep Blue Pools, Alhaurin el Grande, 952 594 393
Copyright Ken Walker, Deep Blue Pools, July 2006