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Swimming Pool Maintenance
Non-Chlorine Shock Treatment
This is simply using a non-chlorine based oxidiser to eliminate the chloramines.
Potassium peroxymonosulphate is the most common; it's also known
as potassium monopersulphate. Follow the instructions on the container. Note that it does not sanitise, it just oxidises chloramines. The similar sounding potassium persulphate is not suitable for
pool shock treatment.
Other non-chlorine shock chemicals are:
Sodium persulphate: Can cause chemical buildup in indoor pools.
Hydrogen peroxide: Just don't let the kids bleach their hair with
Advantages of Potassium Peroxymonosulphate
Disadvantages of Chlorine Shock
Swimming is possible after just half an hour.
6 hours before swimming - normally left overnight.
No undesireable by-products are left.
May leave by-products.
Calcium hypochlorite (a common chlorine shock) leaves calcium
which affects hardness of water.
Cyanuric acid (from ordinary stabilised pool chlorine) affects
acid level (which is what hurts the eyes).
Not affected by sunlight.
Cyanuric acid is added to pool chlorine to prevent it breaking
down in sunlight. (See the Stabilising
page.) Non-stabilised chlorine should be used for shocking to prevent
cyanuric acid buildup, which means another chemical needs to be
Can be added before shocking is needed (ie, a pot at a time)
since it is only used by oxidising chloramines, not killing bacteria.
Cannot pre-shock a pool with chlorine.
Chlorine levels do not need to be known before using, meaning
less need for (expensive) test strips or tablets.
Combined chlorine levels ideally should be accurately measured
to know how much extra chlorine to shock with. This is normally
calculated by measuring free chlorine and total chlorine and finding
the difference (a sometimes complicated process).
Sadly, at time of writing, not all pool shops sell potassium peroxymonosulphate.
One I went into had actually never heard of the stuff, and when asked
if they might consider stocking it in the future said "No, there
isn't a market for it." They were wrong of course, for many reasons.
A few of them:
It has many advantages over chlorine shock treatment (listed above)
which save huge amounts of time treating the pool and in downtime in
which the pool cannot be used. It also saves money on test strips.
It could be argued that test strips didn't have a market before customers
actually knew they existed.
I was a customer looking for it, wanting to buy some. (Therefore
there most definitely is a market for it, even if it's only a
market of one person.)