Discoloration when adding chlorine.

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Lucky

Discoloration when adding chlorine.

Postby Lucky » Tue 15 Mar, 2005 04:07

When adding chlorine to my pool it turns a dark brown, as soon as it hits the water and then scales out onto the fibre glass surface, the only way to remove it is to lower the ph by adding acid and of course I am like a dog chasing its tail. The pool is over 30 years old but I am told that fibre glass does not break down, I never had trouble until about ten years ago. Can anybody please help. :?


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Larry
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Colored water

Postby Larry » Thu 17 Mar, 2005 15:03

When water discolors after the addition of an oxidizer such as chlorine, the cause is almost always metal ions in the water.

The brown color is usually iron but can also be from copper. In a 30-year pool there may be some old metal pipes that are corroding or rusting, adding iron to the pool gradually.

Other common sources of metals are water heaters and copper-based algacides.

Try to get the water tested firstly for iron. If this is negative check for copper. If this, too, does not show a positive reading, perhaps you could give some more info about your pool and someone may have an answer here for you
Lucky

Water discoloration

Postby Lucky » Sun 27 Mar, 2005 23:42

Thanks for the info Larry, I have previously had my water tested for copper and Iron, never the less I took it to town and the test was negative. All my pool pipes are PVC so I shouldn't have any problems there. Two years ago I emptied my pool and filled it with rainwater off my roof as I thought this could be the problem, this was all to no avail, no one around our town seems to have the same problem that I have. The pool manafacturers cannot explain or understand what is happening, I have turned to the internet as the problem is so frustrating and all I want to do is blow the pool up, my wife won't let me.
I don't know if this information is a help, you would be classed as an utter genius if you can fix my problem.
Regards Lucky. :roll: [/b]
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Larry
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Joined: Thu 09 Dec, 2004 20:19
My Pool: Inground concrete 72m2
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Fiberglass sand filter 920mm
Tiled deck

Colored pool water

Postby Larry » Mon 28 Mar, 2005 02:55

When water discolors after the addition of an oxidizer such as chlorine, the cause is almost always metal ions in the water.

We have so far ruled out iron and copper, the two most common problem metals. I still think that the most likely cause is a metal in solution in the water.

Another metal which is frequently known to cause water discoloration is manganese, though the source would seem obscure from what you've said.

Perhaps you could try the following to determine if the problem is fill-water related or not: fill a bucket or similar vessel with fill-water (from the tap or well) and add some chlorine. Does the water discolor in the same way?? If so the problem is with the water you are adding.

If not, it really does seem a mystery. I'll look into this and try find some other possible causes.
Lucky

Water discolouration

Postby Lucky » Tue 29 Mar, 2005 20:43

Thanks again Larry, I have used tap water with chlorine in a bucket with no adverse effects, it all comes down to the water in my pool. It was interesting to hear you say manganese would have an adverse effect suspended in water, as we have a ferro manganese plant at Bell Bay approximately 3 kilometers away and under some wind changes we receive a fine dust, although the local council refute that, I didn't dwell on that to much because the plant was there when I put my pool in and my problem has only been evident the last ten years or so. I have the sediment that has settled out in my buckets of pool water laced with a little chlorine, so I will get that tested.
Have you any knowledge of a chemical that will dissipate or counter any suspended manganese, that I could add to my pool.
I thank you once again for your help.
Regards Lucky.
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Larry
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Joined: Thu 09 Dec, 2004 20:19
My Pool: Inground concrete 72m2
Tiled overflow pool
2 Hp pump mono
Fiberglass sand filter 920mm
Tiled deck

Pool discoloration problem

Postby Larry » Wed 30 Mar, 2005 02:37

I can recommend two things that help solve metal ion problems:
  1. zeolite in your sand filter
  2. metal chelating or sequestering agent

1. The zeolite is able to adsorb metal ions through "ion exchange" and attract the ions like a magnet. It requires periodic regeneration or "washing" with a salt water solution, which will release the metals from the zeolite.

2. A chelating or sequestering agent forms complexes with the metal ions preventing the chlorine from oxidizing them. They are sold commercially with names such as metal out. Your local pool pro could advise you on specifics. If you choose this treatment, your pool will probably require weekly additions of the chemical to be able to isolate any new metals entering the water.

Hope this helps

Larry
Lucky

Water Discolouration

Postby Lucky » Mon 04 Apr, 2005 01:16

Larry I have had my water tested for Manganese and the result was and I quote: 2.27 manganese Milligram per litres. the pool pro rang me and he was unclear what that meant, I only received the result over the phone so I don't have it in front of me I would assume that it was litre and not litres.
To me anything in whole figures is two much, what is your spin on it.
Thanks again Lucky.
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Larry
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Joined: Thu 09 Dec, 2004 20:19
My Pool: Inground concrete 72m2
Tiled overflow pool
2 Hp pump mono
Fiberglass sand filter 920mm
Tiled deck

Manganese in pool water

Postby Larry » Mon 04 Apr, 2005 14:45

Well that's the cause of the problem then. According to the EPA, the maximum level for manganese in drinking water and water systems is 0.05 mg/L (milligrams per liter). See http://www.epa.gov/safewater/mcl.html#sec

We have suffered the effects of manganese in our water mains for a couple of years and unfortunately getting rid of it is rather expensive. The most economical way would be to use zeolite in your sand filter, but this is only a partial solution as the level in your pool is more than 45 times the recommended limit. Using a good commercial chelating/ sequestering agent would also help, but with such a high quantity in the pool, this too would not be a sole solution.

I think trying to address the source may be more effective in the long term.

P.S. mg/L is the same as ppm (parts per million)[/b]
Lucky

Pool Discolouration

Postby Lucky » Mon 18 Apr, 2005 01:12

Thanks again Larry, I am off on my yearly pillgramage to a warmer climate, so I will tackle the problem when I get home in September, the information you have supplied me with has been a great help and I am indebted to you, what part of the world are you situated in ? I am in Tasmania, Australia.
Thanks again, Regards Lucky
vaughanwilliams
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Postby vaughanwilliams » Thu 16 Jun, 2005 08:08

Hey Larry,

You have obviously had some good experiences with Zeolite. We are just now importing Zeolite for our pool business here in Northern Cyprus.

Our Zeolite, comes from Turkey and we have to buy 20 tonnes at a time, so we are hoping it will prove popular.

In your experience, how does the retail price of Zeolite compare to "sand"? :)
regards

Vaughan Williams
Technical Director
Octopus Pools

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