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Evaporation or Leak ?


londoneye

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Hi

Anyone reading this section regularly will have seen that I am a totally paranoid new pool owner ....

I have tried searching but can't find anything on evaporation levels.   We seem to be losing around 1 - 2 cm (closer to 1 actually) a week from the pool.   I think its evaporation, after all its summer, its been reasonable here (between 25 - 27 air temperature) for a couple of weeks, and I can physically see steam (!) over pool in early morning.

OH, on the other hand, is convinced we have a leak, and is now resorting to systematically digging small holes around outside of pool, to check all piping etc.   Whilst I appreciate this is not the most stupid idea in the world, and its best to do it before we lay the patio etc, he is doing my head in with his mole act!   Could anyone confirm what their approximate levels of evaporation are please?   If it makes a difference our pool is roughly 9 x 4.5 metres and 1.2 metres deep.

Also, I asked on another post, but no-one has answered yet, so will try once again, our sand filter pressure does not seem to be increasing substantially, so we are back-washing every two weeks regardless.   What sort of increase in pressure level should I be looking at over a two week period please?

Sorry to ask such stupid questions, sure I will get the hang of all this in due course.    Pool guy if you read this one, will be pm'ing you about automatic dosing soon.

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That sounds like normal evaporation to me.   Try filling a bucket with water, putting it near the pool and see how much that drops.   If it is similar you cannot have a problem.

The filtering all depends on how much rubbish is going into it.   We rarely need to clean ours as we have an abri and clean the bottom with a robot.

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I tend to agree that the 1-2cm loss sounds like possible evaporation. Not knowing what filtration system you use, but are you aware when you both backwash and rinse the water goes to waste and consequently lowers the level your pool.

Baz

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Thank you - aware of the backwash issue, and we do top up pool after backwash.    Its the loss of water between backwash to which I refer.   I also think 1 - 2 cm sounds about right for evaporation so will try to calm down OH.    Will do the bucket trick also, as that is common-sense (which clearly I don't have these days - its funny because I used to !)

After a backwash we have around 0.6 pressure.    After two weeks we have about 0.8 pressure.     We don't seem to get a lot of debris in pool at all; flies primarily.     We hoover bottom about every two days, and I always try to net the top of the pool at least once between each filtering period.    Don't seem to get any leaves either, just seeds, pollen etc, when windy.

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Londoneye

Thanks for your contact.

I am sure with that water level drop that you do not have a leak. 1-2

cm per week is normal and I would expect to see up to 5 cm if there is

a heavy bather load.

An enhancment to the 'bucket trick' is the place the buck on the steps

of the pool submerged so the rim is at the water level, weigh the

bucket down with a brick (or two) and then wait. If the two water

levels are the same, inside and outside the bucket then it is

conclusive and your resident 'mole' can hang up his magnifying glass-

there is definately no leak. If there is a vast difference then you

have more testing to do before you get into a flap. If suggest you then

contact me for more technical help and about Auto dosing and control.

Andrew

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[quote user="Poolguy"]I would expect to see up to 5 cm if there is

a heavy bather load.[/quote]

Especially if you have kids 'swimming'.  They are constantly in and out of the pool to jump in from the side.  Each time they exit the pool they drag out huge volumes of water with them and then splash out even more when they jump back in [6]

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Believe it or not we have only used it twice since we got up and running - too cold !

Tried the bucket and couldn't understand how so much was evaporating in one day - easily explained when I found the dog drinking copiously from it - hmmm - will have to resort to the weighted down in the water bucket now.

Thanks everyone - I think I have persuaded Mr Mole to hang up his spade for the time being ......

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[:D][:D][:D][:D][:D]

You could always stand the bucket on a chair, or muzzle the doggy [Www]? But yes the bucket in the pool is more acurate because the sun don't get at the side of it then and if it's owt like here then it would get quite warm most daze...

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[quote user="londoneye"]

It's a big dog !!!!!!!!!!

Sadly not like where you are weather-wise, hence the reason we have only been in twice ....   Carcassone - nice there - I wish we could have afforded it !!

[/quote]

Tall stool?

Carcassonne, fairly close to us. Not tooo dear where we are though, but a lovely little village all the same!!

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[quote user="londoneye"]

Believe it or not we have only used it twice since we got up and running - too cold !

Tried the bucket and couldn't understand how so much was evaporating in one day - easily explained when I found the dog drinking copiously from it - hmmm - will have to resort to the weighted down in the water bucket now.

Thanks everyone - I think I have persuaded Mr Mole to hang up his spade for the time being ......

[/quote]

Just noticed this about a weighted down bucket. Don't weight it or it will finish up on the bottom and you won't get ANY evaporation. Thread a broom handle through the handle of an almost full bucket and suspend it in one corner, on bricks if needed. Stick a bit of masking tape on the inside of the bucket at the water line. Do the same with the water level in the pool. Bob's yer unkle an Fanny's yer aunt. Know-wot-eye-mean???[8-|]

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Yes we too are in a small village outside Carcassonne, but not the same one unless you are hiding John.

Not many British here just to the north east of it near Conques.   Haven't seen your glider passing, so I guess you are the other side.

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Now now jonzjob I'm not THAT stupid !! (heh heh)

I might tie the dog to the bucket and see how far that gets me.   Only kidding, really appreciate your advice everyone.   Feel quite chilled about it all now - will let you know how I get on with the bricks tied around the dogs neck and the bucket on the side of the pool - OMG was it the other way around ???!!!!!!!!!   Ooops better go and get the dog out now !!!

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To even begin to calculate you need regular readings of a wet and dry thermometer, wind speed and air pressure.  Back when sex was safe and motor racing was dangerous, even I am too old to remember when sex was dirty and the air was clean. I could understand the equations in the following:

 

http://www.thermexcel.com/english/program/pool.htm

 

http://www.rlmartin.com/rspec/whatis/studies_outdoor_inactive.htm

 

Best of luck if you try and work it though. We loose about 1 cm a week in the Giroinde even when it rains.

 

.

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[quote user="Anton Redman"]

 

To even begin to calculate you need regular readings of a wet and dry thermometer, wind speed and air pressure.  Back when sex was safe and motor racing was dangerous, even I am too old to remember when sex was dirty and the air was clean. I could understand the equations in the following:

 

http://www.thermexcel.com/english/program/pool.htm

 

http://www.rlmartin.com/rspec/whatis/studies_outdoor_inactive.htm

 

Best of luck if you try and work it though. We loose about 1 cm a week in the Giroinde even when it rains.

 

.

[/quote]

Not too sure about yer sex life Anton, but are you sure you ain't got a leek?

As for you Andrew, behave and go and watch yer tele!!

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Anton - very illuminating, and I could thoroughly recommend that everyone checks their evaporation rates via this method, which seems quite straightforward and I would assume accurate.

Using the calculation in the second link I have made the evaporation rate to be 63 percent of the ASHRAE value (mind you I did cheat a bit and estimate the wind speed, which I factored in at a bit of a guess at 10mph).   These values seem to lie well within the normalised curve for standard evaporation rates for non heated pools, so I am quite happy with that.

However, just to be double-sure, I will continue to check it with the bucket method !!!!!!!!!!!!!

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