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 Post subject: Green pool
PostPosted: Fri Nov 04, 2016 1:05 pm 
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Location: Herault (34)
We are still using our pool everyday.However with the temperature down to 15, we are surprised that we cannot get rid of the green alge colour which appears to be getting worse.It appears that the more I shock the water the greener it becomes. I clean the sand filter every few days and all appears normal. The ph I keep at 7.2. The clore which has built up is more than BR 6.5 and CL over 3 so plenty of clore, so this increases even more on shocking. I have been leaving the filtration on permanently for 3 days Very expensive for a 110 m/3 pool. we will probably not use the pool once the temp. drops below 10c. I did not want to leave the winterised pool this green over the winter. Any ideas ?. I do not want to drain the pool as this is very expensive. I did drain the pool 5 years ago ( costly!).


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 Post subject: Re: Green pool
PostPosted: Fri Nov 04, 2016 1:12 pm 
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Joined: Tue Feb 03, 2009 12:08 pm
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Location: Zurich/Basel and Suffolk
Things may have moved on, but last time I had a pool with algae (assuming that is what it is) I used a specialist algicide rather than chlorine for 'the kill' and then added flocculant which apparently helps a sand filter catch the algal particles.

But looking on the bright side, you are not alone - http://www.independent.co.uk/sport/olym ... 89616.html

J


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 Post subject: Re: Green pool
PostPosted: Sat Nov 19, 2016 11:20 pm 
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Sorry I am a bit late answering Thomas, not getting much spare time these days.

From the sound of your text you are using packaged chlorine products? Most of these (lent, multi action, choc) contain a stabiliser (cyanuric acid) to prevent the chlorine being burned up by the sun's UV.
Problem is you need some stabiliser 30-50ppm but the level just keeps building up with each tablet addition or choc dose. When the stabiliser gets too high you get symptoms like you describe now.
I don't know what you use to test the water but dip strips are pretty useless and the stabiliser level is actually more important than the pH but is seldom checked.
Chocing a pool is a process and NOT a product. To correctly choc you need to add sufficient chlorine to raise the free chlorine to a point where everything is oxidised out of the water and that can take several days. If your stabiliser level is already high you need to use unstabilised chlorine like Eau de javel from a brico shed at around €12.90 for 20 ltrs.

Depending on the size of your pool and the stabiliser level at the moment will decide the amount of chlorine you will need to choc it successfully. Stabiliser is not easily removed from a pool so a partial drain and replacement of water is generally the way it's done.

Do not use the French pool shop's advice which is to sell you hydrogen peroxide, as you would read on that article it won't make anything better and will dent your wallet quite nicely.

Do not use algaecide either unless it's a copper based one and with copper there is a risk of staining. Regular algaecide will simply use the chlorine up quicker as it tries to burn it out of the water, it's not strong enough to stop algae once it's there. One of the biggest cons of the swimming pool industry!

Chlorine is one of the best and quickest algae killers we have but it's overlooked in favour of the magic bottle solution at greater cost.

Come back with some water figures from an accurate test and we can see what the issues are and how to work to get your pool back working again.

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 Post subject: Re: Green pool
PostPosted: Thu Nov 24, 2016 4:10 pm 
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Joined: Tue Apr 07, 2009 3:19 pm
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Location: Herault (34)
Thanks for the replies. I added the flocculent and the water is now clear.However there are large green patches on the bottom and all the sides.This green does not move with brushing either with a normal brush or a wire one.I shock with tablets and also granules but it still does not affect the green on bottom or sides. The chlore remains very high according to my liquid test set, and I keep the PH at 7.2.I use the sweepy every other day to keep the bottom clean.I will get the Javel which I have used in the past and see if that helps.I thought that Algae could not servive in low temperatures, but I am obviously mistaken.I do notice that the sweepy picks up quite a bit of sand from the filter and wonder if it is working properly as this situation has not happened before in the previous 10 years.


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 Post subject: Re: Green pool
PostPosted: Thu Nov 24, 2016 11:56 pm 
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Hi Thomas,
The liquid test you have only measures total chlorine and not free available chlorine.
Let me explain, you need free available chlorine to do the work of sanitising your pool water. When the chlorine gets used up it forms other chemical compounds known as chloramines or disinfection by-products (DBP's) it is perfectly possible to have a high level of DBP's and no free available chlorine but the best situation is to have free available chlorine and no DBP's

To test for free available chlorine you need a DPD1 test (common tablet test), you can use your liquid test (OTO, check the label) to read the total chlorine, you subtract the free available chlorine form the total chlorine and you have the nasty combined chlorine (DBP's) you don't want. The reading for combined chlorine should be 0 to 0.5ppm over that and choc'ing is advised.

Unfortunately the oldest form of plant on the planet can survive very cold water, they just don't multiply as fast but they do survive just waiting for the spring to bloom again. Lowering the nutrient levels in the pool and keeping the chlorine level up is the best form of defence.

Now you say the green won't budge with a brush or wire brush so you haven't a liner pool, so a plaster or tiled finish? Green is most likely well attached algae but could also be dissolved metals in the water that have come of of solution and stained however if you keep the pH to 7.2 this shouldn't happen but can if the brushing of the pool surface exposed a fresh high pH plaster or grout.

If you can get a proper water analysis done it would help to see where your levels are but make sure if the pool shop do it they are not using dip strips behind the scenes as so many do in France. You need a photometer or colourimeter test Green could be an excess of copper or another metal although once it has plated out on to the pool surfaces it doesn't always show on the tests. Using a vitamin C tablet on the stain will often make it vanish after a few minutes, chlorine will bring it back again.
Let us know how you get on.

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 Post subject: Re: Green pool
PostPosted: Fri Nov 25, 2016 3:55 pm 
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Location: Herault (34)
Hi Teapot. Many thanks for your reply. I have arranged a visit from a pool man to analyse the water properly. I will let you know what happens.The pool is a plaster finish. Regards Thomas.


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 Post subject: Re: Green pool
PostPosted: Sat Nov 26, 2016 12:10 pm 
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Location: Herault (34)
Hi Tpot. The pool man arrived and measured using a digital system. He measured the stabiliser. It was off the scale and far too much. He suggested draining the pool and starting again with non stabilised chlore.However he recommended that I consider using a salt system rather than the chlore.He could not speak English and I could not really understand how salt is used for this pool and the quantities required ( 110 m3 pool). I will drain the pool now for the winter and start again around end of march, this time using salt. Knowing the corrosive properties of salt I am a bit concerned over the effects it could have on the filtration system. Look forwards to your thoughts. Regards Thomas.


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 Post subject: Re: Green pool
PostPosted: Sat Nov 26, 2016 5:51 pm 
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Hi Thomas,
Off the scale rather depends on how high his scale goes, any actual numbers?. Personally I wouldn't drain it now, this side of winter.
There are a couple of reason why but it also depends if you have a cover for winter.
Over winter when it gets very cold, sometimes an obliging bacteria comes by which eats the stabiliser, very obliging of it. This may be somewhat rare but it can happen.
If the level were say 200ppm of stabiliser emptying 3/4 quarters would leave you with the 50ppm you want.
As you have some green, I would add eau de javel around 60 litres of it, this will get to work on the algae but will also begin to oxidise the stabiliser as well lowering the level and it will only cost you around €40. You may well need to repeat this exercise again but would still be cheaper than emptying I would think.
Please come back with the other water figures from your test and if it's not a rude question how much was the visit?
We can discuss salt generated chlorine later, yes it's still a chlorine pool, you just generate the chlorine on site rather than purchasing from a Brico etc.

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 Post subject: Re: Green pool
PostPosted: Sat Nov 26, 2016 8:11 pm 
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Location: somewhere in the "pays de dropt"
Not being a professional pool chap but having built and maintained a number both here and in the UK, I would never drain a pool for the winter only below the inlet and the outlet skimmers.
If you get a hard frost or a very wet winter you will have loads of problems, either frost damage or the walls being damaged by water pressure from outside.
Know this from clients who didn't listen and drained down, but with your on going problems I'd certainty do so early spring and start again.

With plastic pipework there's no problem with a salt system, cheaper and easy to maintain, have used it here in France a couple of times and with gites ( and myself) no stink of chlorine, but you will still have algae problems after a thunderstorm, comes like many other stuff in the rain, tomatoes blight for instance.

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 Post subject: Re: Green pool
PostPosted: Sun Nov 27, 2016 10:07 am 
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Exactly Papibryn, bad idea draing at this time of year.

Moving on to the contentious part of salt chlorination or direct chlorination.
In France if your pool is used for a gite/hotel etc you cannot use a salt system. The reason is simple and as Papibryn said it won't stop it going green after thunderstorms because they only trickle a tiny bit of chlorine in and it often can't keep up with what is needed to keep the pool sanitised and algae free and it also cannot cope with sudden increases in bather numbers. Use the performance figures quoted by manufacturers as the best and maximum, better to go over size.
With a salt system you are introducing an element of automation that the tablet dissolving doesn't have. Equally if you go for a direct chlorine dosing system it also gets easier.
Cost wise is similar with direct dosing or salt.
Salt chlorinator is moderately expensive to buy circa €800-1200 and uses electricity to run it. The salt cell has a finite life span 5-7 years and cost a fair bit to replace circa €500. Modern units use efficient power supplies but these do not last as long as the older inefficient units. A bag or two of salt at the start of each season €12 per bag
For a similar amount of money you can get a direct dosing unit. the dosing pumps need the feed tubes replacing each season to be safe but certainly every two seasons €8 but you do have to buy your eau de javel so trips to Bricos should be costed in, if you live close this could be less than say the replacement salt cell over 5 years, if you have a long drive then could be more.

Good units have probes for testing the chlorine levels on salt systems and direct dosing systems, these wear out and need replacing every couple of years. NOTE: do not buy cheap probes off Ebay, these last a few months and could cause serious accidents like emptying 15 litres of pH- acid into the pool turning it into swimming in lemon juice, Ouch!

With salt chlorine generators the process causes little bubbles of hydrogen to be given off, these bubbles cause a drift upwards in the pH of the pool so you need a pH dosing unit to bring this back under control. Although a lot of direct dosing units have this pH doser built in direct dosing doesn't suffer from the same pH drift.

Forget about the sales blurb and natural soft water blah blah it's the same chemical soup and the adverts conveniently forget you still have to handle nasty pH- (hydrochloric acid)

Hopefully an overview of both systems, bound to raise more questions and comments, not a problem.

Back to the pool, the pump may not be rated for use in salt pools, some are some are not, due to the corrosive nature of salty water it can cause premature failure if not rated for salt.
Stainless steel ladders can also suffer as can stainless steel screws used on fittings. There are different grades of stainless steel and A2 is most commonly used but a salt pool should really have A4 marine grade.

"No stink of chlorine"
Chlorine doesn't stink, sniff a container of bleach, very little smell just like a well run pool. Chlorine reacts with organics producing as I described previously chloramines (DBP's) these smell as we remember from school swimming trips of the "stink of chlorine" caused by a build up of bad combined chlorine (DBP's) both salt chlorinated and direct dosing pools should not smell, even manually dosed with tablets should not smell, if they do you need to do something about it as the pool is unhealthy.
That's enough from me in one session :-@ :-@

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 Post subject: Re: Green pool
PostPosted: Sun Nov 27, 2016 11:38 am 
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Location: Herault (34)
Thanks both for your very welcome reply. I did not think of asking the man for the actual figures as I should have done.He was here for around 20 mins and he charged 40 e. I will take your advice and not drain the pool completely until the spring. I last drained it about 5 years ago and worked out the cost of the water at around 600 e. so will leave about a meter in the pool when I do. (12 x 8 ).Should I add the Javel before I drain it or when it is refilled?.The idea of a salt system appeals , but I wonder about the cost for the extra equipment this system would require. Regards Thomas


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 Post subject: Re: Green pool
PostPosted: Sun Nov 27, 2016 5:48 pm 
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Once you call out a a man who can and any of my customers who do, get handed a full water report, its just the way it should be done. Did they only carry out one test?
Now you know the value of testing with better equipment may be you can equate having your own for just a shade less than four visits from this chap? If you had been aware of the stabiliser getting too high or any other parameter going out of range you could have cured the problem and not now be facing the increased cost of a water change, it's a point I have been trying to get over to owners for years.

To avoid the pool possibly becoming a swamp over winter, I would add the javel now and get on top of the water situation. You may need to add more again in a few weeks but that will oxidise some of the stabiliser out of the pool and could necessitate a much smaller or none at all water swap come the spring.

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 Post subject: Re: Green pool
PostPosted: Wed Nov 30, 2016 3:53 pm 
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Location: Herault (34)
I put in the 60 litres of Javel in yesterday, and kept the system on. I will let you know the results.I looked at digital testers and they all look a bit expensive.Perhaps there must be a simpler tester along the lines of the common liquid type.I did see on google a type with a dot in a test tube which might be available.


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 Post subject: Re: Green pool
PostPosted: Wed Nov 30, 2016 4:08 pm 
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Hi Thomas, the tester for stabiliser that you refer to is the vanishing dot type, on their own they are low cost and effective. £28 ish including postage. That however is only one of the water parameters that you really ought to be testing for. The others are free chlorine, total chlorine, alkalinity and hardness with are important to any plaster or tiled finish pool. The best value tester to cover these are around £158 with enough reagents to cover a few years. There are cheaper models available but the come with far less reagents so by the time you have added in the extras they are more expensive, just clever marketing. Thats the electronic version. There is a slightly cheaper version called a comparator but you have to match the colours with those.

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 Post subject: Re: Green pool
PostPosted: Fri Dec 09, 2016 3:59 pm 
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Location: Herault (34)
Hi again. The Javel did clear up the water, however the green remained in patches on the bottom and walls although at least a bit fainter. I decided to drain the pool down to half way ready for winter. The green remains on the exposed dry walls, and perhaps will take some time to go.I will probably invest in one of the digital testers for next year. They appear to be only available from the states.I will probably drain a bit more before I eventually refill early next year since reading the warning about leaving a drained pool for a long time.Many thanks for your help I will keep in touch. Compliments of the season to all.


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 Post subject: Re: Green pool
PostPosted: Mon Dec 12, 2016 11:13 pm 
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Hi Thomas,
Yes javel can do so much but you can't get patience in a bottle ;) Normally draining 50% of a pool is a bit much but with your high stabiliser level it will speed things up come the spring. Javel will, given winter time have time to oxidise the stabiliser down to a sensible level without draining.
If pool builders were not so thick they would connect up the over flows fitted to most skimmers which negates the need to drain down at all, give them another 10 years maybe they will get it :((
Regarding the electronic testers, naturally enough I wouldn't suggest something that wasn't available in the UK/EU and It's my friends company that is the main agent and I am one of his agents, buying from the USA means no warranty outside the USA but buying a UK/EU model you do get the warranty. Costs once you add in the import duty and TVA/VAT mean the prices are pretty similar depending on exchange rates at the time. + you get helpful advice from me O:-)
Yes seasons greetings to all and speak again in the spring.

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