Problem - Threw Chlorine In Pool & It Turned Purple/black

[EeL]

Hi there

First off Merry Christmas/Happy Holidays to anyone who reads this! Anyway, I was just cleaning my inground swimming pool and finished it off with some pool chlorine dust. I left after I finished to bathe and whatnot and happened to walk by the pool again and saw that everywhere chlorine was thrown had turned purple/black! I tried to sweep it off but it's like fused with the ground! Any information on this strange occurrence would be helpful! I've been cleaning my pool for more than 7 years and never encountered or witness anything like this! How do I fix this!?

Thank you for the help!

[chem geek]

Does it look like what is seen in this link? If so, then the chlorine product you used may have had copper in it and if your Cyanuric Acid (CYA) level is very high then the purple precipitate is copper cyanurate. Lowering the pH can help to dissolve it, but if you have a lot of copper in your pool then you'll need to remove that with partial drain/refills and then may need to use a metal sequestrant to keep its effective concentration lower. Do you have the package your chlorine product came in? Does it have an ingredients list? What is the full name of the product and its manufacturer? We can try and look up its MSDS to find out its ingredients.

The other possibility is manganese which can form purple water and stains though usually with chlorine it turns more black. Again, lowering the pH and using a metal sequestrant can help. However, since this came on rather suddenly, I suspect it's copper in what you added since any manganese should have already been in your water, coming from the original fill water.

[waterbear]

First question, is your pool plaster or fiberglass?

Second question, have you used any metal based algaecides?

Third question, exactly what chlorine did you add--dichlor, cal hypo, or lithium--and why didn't you predissolve it first?

Fourth question, do you have a current set of test results NOT done with strips you can pose? If you have any test results for metals please include them.

As an educated guess it sounds like metal staining, most likely from copper, manganese, or cobalt (although the first two are more likely).

It is not a strange occurrence at all and is what happens when chlorine reacts with metal ions and oxidizes them into a colored state that stains. Prevention is better than trying to fix it after but if you post the info above we can give you some pointers on how to proceed.

[waterbear]

I see chem geek and I are on the same page!

[EeL]

Honestly at waterbear, I have no idea. I just clean the pool the way my dad told me and I've been doing it like that for years and this never happened. Anyway I found out what I could:

We use:

Clear Swim Unstabilized Granule Chlorine

Clear Swim Stabilized Chlorine Tablets

Pool Blocks - All Season Algaecide

This is the order of how cleaning the pool would go:

Vacuum the pool

Backwash

Rinse

Take leaves etc. out, clear filter basket, put chlorine tablets/pool blocks into filter basket, throw granule chlorine into pool

Start the pump to filter again

So what happened was I followed that procedure above and after leaving the pool for a while and seeing it again the parts where I threw the chlorine and where it fell to the pool floor were purple-black.

The weird thing is that after a day it just disappeared. The pool went back to normal, even when we tried to sweep the areas affected, it wouldn't come off then the day after it just vanished. I really just want to know whether the pool is usable or not and what happened.

It didn't look like the picture provided it was a really dark colour.

Thank you so much for the help!

Note: I don't think anything is wrong with the chlorine, we've been using the same brand for years plus I used some from the very same bucket like twice before this incident and nothing happened. I did read about the metals in the pool, but how would the water just get a lot of metal randomly after nothing changed? That's what I'm confused about.

[waterbear]

Please post a full set of test results. I have some ideas but without knowing ab it about the water chemistry it's pointless.

Is the pool plaster (cement, gunite, shotcrete, marcite, exposed aggregate, etc.) or is it fiberglass (smooth, platic feeling one piece pool shell with molded in steps and such)?

I can tell you this, you have copper in your water since the algaecide you use is copper based and when the chlorine granules (most likely cal hypo which is slow dissolving) landed on the pool surface they oxidized the copper in the water or that had already depostied on the pool surface into a black, oxidized copper form that stained.

Copper builds up over time and it does not go away. As water chemistry changes it deposits as stain on pools and people, It is what turns hair green.

I suggest you start testing your water and getting it balanced because properly balanced and cared for water will not have the type of problems you describe.

Where are you located? You IP address is Trinidad/Tobago.

[EeL]

I am located in Trinidad. I don't think I have a water test sample thing but my dad might have bought it and never used it, I will check. So you're saying that the algaecide is what introduced the copper into the water? Then how do I get rid of the copper in the water and why did the stains just disappear? Is the water safe to use? Please post the theories you think are the most plausible with what little information you have right now while I try and get more information in about the pool and the water.

UPDATE: My dad says that it is cement but there's something over it though, he didn't remember the name but it was something like "StarBright" or something like that, he can't remember.

[waterbear]

I am located in Trinidad. I don't think I have a water test sample thing but my dad might have bought it and never used it, I will check. So you're saying that the algaecide is what introduced the copper into the water? Then how do I get rid of the copper in the water and why did the stains just disappear? Is the water safe to use? Please post the theories you think are the most plausible with what little information you have right now while I try and get more information in about the pool and the water.

UPDATE: My dad says that it is cement but there's something over it though, he didn't remember the name but it was something like "StarBright" or something like that, he can't remember.

Only way to get rid of copper is to replace water. The stains probably disappeared becasuse of a drop in pH from your trichlor useage. I suspect that your TA and pH ae extremely low from continued trichlor use and never testing the water.

Is the water safe? Good question. Depends on the free chlorine level, pH, copper level, cyanuric acid level and other water parameters. You cannot just keep dumping chlorine and copper into a pool and never test the water nor adjust pH or total alkalinity or monitor calcium hardness and saturation index and not expect problems. You have a plaster surface pool (I suspect it is an exposed aggregate finish) btw and if you do not want to damage the surface you must be aware of your pH , calcium, total alkalinity, and saturation index!

[PoolGuyNJ]

There is a relatively new way to remove metals from pool water. It s a pouched product that gets tossed in the skimmer (up to two per skimmer) called CuLater:

Here is their You Tube:

Here is their web site: http://www.culator.com/

In The Swim has it too.

A Google of "CuLater metal remover" yields: https://www.google.com/search?q=CuLater+metal+remover&ie=utf-8&oe=utf-8&aq=t&rls=org.mozilla:en-US:official&client=firefox-a

Scott

[waterbear]

There is a relatively new way to remove metals from pool water. It s a pouched product that gets tossed in the skimmer (up to two per skimmer) called CuLater:

Here is their You Tube:

Here is their web site: http://www.culator.com/

In The Swim has it too.

A Google of "CuLater metal remover" yields: https://www.google.c...lient=firefox-a

Scott

After some users in another forum tried CULator the jury still seems out on its effectiveness. Some have reported it worked and others said that it had not effect. I have no personal experience with the product but just am reporting what others have said. In theory it should work to bind and remove metal ions from the water.

Only time will tell if this is truly a useful product or another 'snake oil' like pool magnets and ionizers.

[EeL]

OK, I've found out that the pH is 6.5 or a bit lower. Also the people at the pool store just told my dad to drain the pool about 1/3 and that should get rid of the copper in it. Will it be safe to use after the draining and can someone tell me what chemical reactions were really going on with the chlorine and water?

[waterbear]

OK, I've found out that the pH is 6.5 or a bit lower. Also the people at the pool store just told my dad to drain the pool about 1/3 and that should get rid of the copper in it. Will it be safe to use after the draining and can someone tell me what chemical reactions were really going on with the chlorine and water?

AS far as the staining, the chlorine oxidized the copper into an oxidation state that stained. It happened in spots because you broadcast a granular chlorine that settled on the pool surface so there were many localized high chlorine areas as it dissolved, causing the spots.

You have been using a copper based algaecide and the low pH could also have dissolved copper from plumbing or a heater if you have one.

The low pH could be caused by a number of things and without knowing exactly what chlorine chemical(s) you are using and a full set of test results, including TA and CYA (cyanuric acid, stabilizer) it's just about impossible to say but i will make an educated guess:

1. you do not test your water nor balance it

2. You have been used or did use an acidic chlorine source (dichlor granules or trichlor tablets or granules).

3. You do not monitor TA nor maintain the total alkalinity in the proper range.

The problems you encountered are really just bad water management and should not have happened. I suggest you start educatiing yourself on proper pool care and get yourself a good test kit. LaMotte, Palintest, and Taylor (which is availabe through their worldwide distributors, HornerExpress) are ones to look into. If you can get it I would recommend the Taylor K-2006 kit.

AS far as draining 1/3 of the water to remove the copper, dilution will remove some. As far as whether the water is safe, that depends on just how high it is and you can only determine that by testing the copper level of the water.

[Henry Ortiz]

Can i swim in a purple stained pool is it safe