Length of pool (metres) 25Width of pool (metres) 13Depth of shallow end (metres) 1Depth of deep end (metres) 2Average depth 1.5Surface area (square metres) 325Pool volume (cubic metres) 488Total max. Instantaneous bather load 101Max. Operational daily bathing load 605Design circulation/flow rate (cubic metres per hour) 171Design turnover period (hours) 2.84Weekly fresh water dilution required (cubic metres) 127

Number of filters 2Width of filter (metres) 2.2Actual circulation/flow rate (cubic metrs per hour) 170Filtration rate of each filter (metres per hour) 22Actual turnover period (hours) 2.87

The often used figure of 3 square metres per bather, per day is a starting point for health and safety purposes only. For design purposes, the depth of the water needs to be taken into account also, and is what is caculated for you in this figure.

Water under 1m deep: 2.2 square metresWater between 1-1.5m: deep 2.7 square metresWater over 1.5m deep: 4.0 square metres

Your pump(s) should be in sufficient number and size to deliver this circulation rate.

For a typical public pool of 25m length, the turnover rate should be between 2.5 - 3.0 hours

If you're not diluting this much due to backwashing, you need to look at additional dilution measures (feeding pre-swim showers from pool water would be an economical option).

If you have a flow meter fitted you can enter the circulationrate here. Your actual circulation rate might vary from the design circulation rate, especially on older installations from an era with different standards and specifications etc.

This is the recommended maximum amount of bathers per day. If your plant was originally designed for school use, but you are now also open for community use, you may already be exceeding this figure.

For municipal, public swimming pools, the filtration rate should be between 10 - 25 metres per hour. Any higher and filtration will not be sufficient. Any lower requires filters that are too large for the plant room.

The information and measurements above are based on recommendations by the Pool Water Treatment Advisory Group. They are what a pool plant system should ideally be capable of. By providing some additional information in the white boxes below, you will be able to see what your pool plant system is actually delivering. In modern pools, the performance of the system should measure up , but in older pools, don't be surprised if they don't. For example, a pool that was constructed back in the 80's, intended for school use only and light bather loads, but after a few years decides to extend its use to the wider community, might find that its turnover period is far longer than the recommended 2.5 - 3 hours. This will make it more of a challenge for the pool operator to maintain ideal pool water conditions.

This interactive management tool has been developed by Stockwell Associates, using data supplied by the Pool Water Treatment Advisory Group (PWTAG). If you require any assistance, please call Stockwell Associates on 01925 753 228, or visit our website; www.stockwellassociates.co.uk.