The most important feature of any swimming pool is that the water must be 100% safe at all times, writes Chris Carr, a former president of the Institute Of Swimming Pool Engineers. In order to ensure that this is the case, satisfactory filtration with correct sanitation, monitored by accurate water testing is absolutely essential. Whilst a typical swimming pool filter unit may produce excellent results on its own, there are times when it could do with a little help by means of flocculation.
This is especially the case when a pool may be opened after a winter closure or other times when the pool may have had excessive use, or been contaminated by fine debris causing the water to appear dull or possibly cloudy. Today, the standard for quality of swimming pool water in the UK is set by the: Pool Water Treatment Advisory Group (PWTAG) and the current standard for turbidity (clarity) published by them is: 0.5 NTU (Nephelometric Turbidity Units). It is vital that this standard is adhered to at all times to ensure the health safety of the bathers using the pool.
So how should you ensure that the correct clarity is maintained, I hear you ask. Firstly, look at the pool water, can you see the bottom clearly in the deepest area? Does the water look dull or cloudy? Beyond that; it is a good policy to regularly test the water turbidity as it is just as important as checking the pH and chemical levels. So it would be well worthwhile to invest in some reliable and accurate test equipment.
Today there are some excellent products available for testing pool water clarity and resolving any problems that may arise. If the water turbidity is outside the standard set by the PWTAG then a suitable flocculent is the most practical way to resolve the problem. But how well does the testing equipment and flocculent work? So we decided to put it to the test. Here in the UK, we are fortunate to have the largest and most successful swimming pool cover material manufacturers based down in sunny Sussex, namely Plastipack Ltd. It is impressive to learn that Plastipack supply swimming pool cover material to over 50 countries worldwide, and as far afield as Brazil to the west and India in the east.
Plastipack have made a massive investment in testing their cover material products and currently they have five identical test swimming pools on site at their factory in St Leonards on Sea. Plastipack’s research and development manager – Tim Fielder who was only too happy to assist and he agreed to arrange for daily turbidity testing on two of their test pools.For the test we decided to use a very popular flocculent used for swimming pool filtration, namely MSI’s Jolly Gel. Plastipack agreed to provide two of their test pools, being 004 (appearing visually good) and 005 (appearing visually cloudy). To ensure our test results were accurate we enlisted the assistance of Colin Day FISPE – sales manager of The Tintometer Ltd. As well as being an expert on water chemistry, Colin is also the current President of the Institute of Swimming Pool Engineers. Colin bought along a brand new Tintometer turbidity meter and gave some very useful on-site training to all involved.
Colin went on to stress the importance of measuring the pH and chlorine levels at different areas around the pool, as if they were not properly controlled they could adversely affect the results. Additionally, Colin took turbidity test samples from several areas around the pool, and it became evident that the highest turbidity readings were from the deepest part of the pool, so it was agreed that this would be the best place to take samples for the ongoing tests.
Flocculation and the improvement of turbidity levels is not instant and usually takes a few days to reach optimum levels, so to monitor the turbidity levels on a daily basis and relay the results to Chris Carr for analysis. An important point to note is that for the flocculent to work at its optimum the water temperature ideally be over 20°C to ensure effective results. The turbidity testing took place over five day period and the results were quite impressive as you will see from the graph below. Whilst test pool No 4 started out looking visually good with a turbidity reading of 0.4NTU (being 0.1 NTU below the PWTAG Standard), even so Jolly Gel managed to improve the water clarity by taking the level down to: 0.27NTU which is well below the 0.5NTU standard set by the PWTAG.
Perhaps even more impressive was the results for pool No 5, as this pool was initially in a very poor condition with a turbidity reading of: 1.28 NTU. After just four days the turbidity level in this pool was reduce to 0.28NTU and although there was a slight rise at the end of five days it was still within the 0.5NTU Standard set by the PWTAG. It is worth bearing in mind that these test pools are outdoor and can be affected by wind born pollution which we believe is the reason why there was a slight increase in the turbidity reading for pool No 5. In any event, the results prove that the Jolly Gel flocculent works extremely well and is an excellent way to give your pool water that extra sparkle.
Chris Carr Filtration Services