Lightning

[Tarrot]

At the start of this season, as a completely novice pool owner, I got some good advice from forum members.  I thought I'd share the following experience.  We awoke the other morning to find the circuit breaker on one phase of our power supply had tripped.  We assumed this was a result of the usual Summer storms and in particular the enormous clap of thunder that had woken us up in the night.  The circuit was easily re-set.  The pool house is one of the things on that circuit.     

Later that morning I noticed a huge black swirl across the surface of the pool.  It ran all down one side.  It actually looked quite pretty - like a garland of black flowers.  Closer examination showed it was made of very fine soot.  I collected some of it by hand (a few ounces actually) off the top of the water. The rest was extracted, also by hand, in the skimmer a bit at a time.

I can only assume that the pool was struck by lightning - which is rather a scary thought.  Does this happen often?

[Théière]

Oh crikey, are you on a hill?

Well apart from the black soot the ozone generated from the lightning should certainly have sterilised the water.

Generally the surface area of a pool is quite small so quite rare that pools get hit and also they are not often the highest point except maybe above ground pools.

Did you notice any difference in the chemical levels post strike?

[Tarrot]

Not on a hill, but lots of very high trees nearby.  I am going to do the chemical tests tomorrow.  I have a copper / silver electrode system and was worried about the effect of a million volts or so on that, but it seems to working okay. 

[Théière]

Hmm, despite the high voltage it appears to dissipate very quickly so hopefully the distance from the pool to the power unit saved it.

Hopefully you use a little chlorine with your ioniser to keep the water in top condition and to fully sanitise the pool.

[andyh4]

I am just wondring how lightning striking water is going to produce soot (carbon)

[Théière]

There are a lot of carbonates in the water + organics

[andyh4]

I think you would need carbonate soup to have a "huge black swirl" - sorry it does not add up.  As for the organics - I doubt it but have never seen an an analysis.

[Théière]

Some small hapless animal taking a swim at the wrong time? who knows.

[nomoss]

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[andyh4]

That does not hold water (sorry pun not intended) either.  Think of people who get struck by lightning, they end up with burns but are not carbonised.

 

Although there is a massive amount of energy in a lightning bolt, anything related to the pool and its water directly would imply that if there is energy to carbonise something completely, a large amount of the pool water would have had to have boiled away at the same time.

 

More likely some burning paper caught in the wind has landed in the pool.

[Tarrot]

Sorry I have not checked the web for a while or I would have responded earlier.  I was puzzled as well, but it really was very fine soot.  And quite a lot of it too. It was too big (imagine a fan about five feet long) and too regular to be burning paper. I've since found a mark on the liner at the bottom of the pool (the deep end).  I'll try and do a bit more research on the physics of this mystery.  All I've turned up so far is a news item about some poor chap in Italy who was killed by lightning sitting with his legs dangling in the water.

And yes, I add a little chlorine and the tests were okay, although the water was a tiny bit more acid than usual.

[Rabbie]

I wonder if the soot could have come from some oil floating on the surface. Not so surprised at the higher acidity. Lightning is a major producer of nitric acid.

[Théière]

[quote user="Tarrot"]Sorry I have not checked the web for a while or I would have responded earlier.  I was puzzled as well, but it really was very fine soot.  And quite a lot of it too. It was too big (imagine a fan about five feet long) and too regular to be burning paper. I've since found a mark on the liner at the bottom of the pool (the deep end).  I'll try and do a bit more research on the physics of this mystery.  All I've turned up so far is a news item about some poor chap in Italy who was killed by lightning sitting with his legs dangling in the water.
And yes, I add a little chlorine and the tests were okay, although the water was a tiny bit more acid than usual.
[/quote]

Lightning doesn't penetrate that deep which is why in lakes the fish survive such attacks so interested to know what that is lurking in the deep end. Some good news if it's nitric acid it will clean your filter [:)] just not sure where the dirt may end up.