HOW TO DEAL WITH A SWIMMING POOL FLOODED WITH MUDDY WATER
Complete Pool Controls Ltd
Supplying a comprehensive solution for the treatment and dosing of recreational water via an extensive UK dealer network
As ever with the weather and we do love talking about the weather don’t we, the seasons do seem to reach extremes from time to time. Something that we often hear about around the country are rising flood waters, rivers bursting their banks and the effect that this has on businesses and families.
Rising flood waters could also affect a swimming pool.
A Worcestershire Leisure Centre was once completely overcome by floodwater, the plant room, being sub terrane an was completely submerged, and the moving floor swimming pool contaminated with river water.
On a smaller scale this could also happen to an outdoor pool that is next to a river or stream.
If this has happened, then there are steps that you could take to tidy up the mess that is left behind.
Firstly, DO NOT BE TEMPTED TO DRAIN THE POOL. The water table will likely be very high, and you could cause catastrophic damage to your pool shell and pipe work. Imagine trying to press an empty bucket, open end up, down into a body of water - as soon as you let go it pops straight back up. That is what a swimming pool shell would do, it would try to float out of the ground without the weight of water to keep it down.
Hopefully, the swimming pool pump and filter will have escaped damage, if not then your local pool company will need to fit a new pump and maybe change the filter media too, plus any other effected components.
Once the pool pump can be run again, the pool filter should be set to Recirc. This will draw water from the pool, through the pump, but it will not be passed through the filter media. It would be advisable to only draw water from the skimmers and not from the sumps at this stage.
Check to ensure that water is circulating and that the underground pipes are not blocked with silt or any other debris.
With the water circulating use Blue Horizons Granular Floc and broadcast this product in accordance with the dose instructions evenly across the surface of the pool using a watering can and a rose head or spreader bar attachment.
Wherever the granular floc solution lands in the surface of the pool, it will fall to the bottom in that place, collecting particles as it does so. After adding all the granular floc – it may need to be added in 3 or 4, or even more, doses depending on the size of the pool - and the watering can!
Once it has been all mixed and broadcast across the pool water surface, allow the pump to run for 30 mins (in recirculation mode) and then turn off the pump.
Leave the pool for 12 – 24 hours to allow the debris to fall to the bottom of the pool.
The pool water should now be clear and the debris clearly visible on the bottom trapped within a colloidal substance.
At this point an assessment can be made on how best to clear the base of the pool.
If the debris is light (1” – 2”) then it would be possible, by manually topping the pool up with a hosepipe, to vacuum to waste. This will remove the silt and send it to the drain.
Whilst still in waste mode the sump and skimmers lines could be opened and left to run individually to clear them of debris and silt.
Once the sump and skimmer lines are cleared the pool could operated in its normal filter mode.
It will be very important to shock dose the water to ensure that any bacteria that could be present as a result of the floodwater are killed. The most harmful of which would be Cryptosporidium*
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Given the criteria that most domestic pool filtration systems are designed to, they will have high-rate filtration and as a result will only remove as little as 10% of crypto on each pass. In accordance with PWTAG** guidelines super chlorination, or shock dosing should take place to ensure the removal of any Crypto oocysts.
To effectively shock, the pH level will need to be 7.2, lower if possible and unstabilised chlorine*** should be added to achieve and maintain 20ppm for 13 hours.
How to get 20ppm accurately into the pool water??
The following information needs to be known:
A = V x ppm so A = 45 x 20 = 1285.71g
CL 0.7
1.285kg of 70% rapid shock will be required to get 45m3 to 20ppm.
If liquid chlorine at 14 / 15% is to be used then the calculation would be:
A = 45 x 20 = 6000ml
0.15
6.0 litres of 14/15% liquid chlorine would be required
To be certain that there is no cryptosporidium present in the pool water and to confirm the procedures that have been carried out have been effective a water sample could be sent for microbiological analysis.
*Cryptosporidiosis (also known as "Crypto") is a s a disease that causes watery diarrhea. It is caused by microscopic germs—parasites called Cryptosporidium that can be present in the soil and that come from animal and human faeces.
**PWTAG – Pool Water Treatment Advisory Group www.pwtag.org
***Unstabilised chlorine contains no cyanuric acid. Unstabilised chlorine products are typically either calcium hypochlorite granules or sodium hypochlorite liquid. Examples of these products are: