Pool turned bright green overnight

Ron55

Active member
Jun 23, 2013
34
Long Island, NY
Yesterday my pool was crystal clear and here are the stats.

27,000 gal Vinyl lined pool
TC 1.0
FC 0.2
CYA 60
CH 100
Ph 7.6
Alk 60

I noticed the chlorine was down to 0 from a lot of bright sun and rain so I added some old tabs to the chlorinator (first mistake) instead of adding liquid chlorine. I need to add some water as well and I used a new hose I had.

Woke up this morning and the water was still clear but bight green. I thought maybe copper leached into the pool from the new hose as it is one of those collapsible hoses made from copper thread (2nd mistake).

I have a test kit but not the ability to test for metals so brought it to a local pool store who tested water and it was 0 for both copper and Iron. Pool store people thought it was an algae bloom. Phosphates were also high at 270.

Recommendations?

Thank you.
 

mknauss

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If it is clear and green, nearly always iron.

Put some paper towels or polyfill in the skimmer. See if they turn brown.

Not that they matter, but that level of phosphates is really low. If well over 2000ppb, they might make a difference.
 

duraleigh

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Almost surely iron in your pool water. Do you fill from a well?

polyfill will eventually capture it and your pool will turn blue again but you will still have the source of iron to deal with.
 

Ron55

Active member
Jun 23, 2013
34
Long Island, NY
Thanks for the reply. I tried the paper towel in the skimmer. It is still white with no brown at all.

The pool store ran two tests for iron. One used a machine and then they checked with a strip. Both showed no iron and no copper.

I asked the guy who does my pool repairs and he suggested I treat it like algae first. Bring the chlorine to a high level and then add a 60/40 algaecide.

He also said if that doesn't clear it up to take a vitamin C tablet in the shallow end and rub it against the liner to see if the line is stained from copper.
 

Ron55

Active member
Jun 23, 2013
34
Long Island, NY
Thanks. It's municipal water not from a well. Have had this pool for 15 years never had a metal issue before.
As I said they double tested for copper and iron and both came back near zero.

Maybe the tests were wrong? Could the water leached from the hose I used? Its an expandable hose supposedly made from copper fiber.


Almost surely iron in your pool water. Do you fill from a well?

polyfill will eventually capture it and your pool will turn blue again but you will still have the source of iron to deal with.
 

mknauss

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Great.

Another member on Long Island mentioned he had copper in his tap water. Something about much of the water system being copper lines, etc.

So you might have some copper. Not sure why the pool store could not pick it up.

Did you lower your pH to 7.2 prior to starting the SLAM?
 

duraleigh

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Copper DOES NOT turn your pool green like you describe. It precipitates as a bluish blackish stain onto surfaces and does not stay suspended in the water.

If the water is as you describe and it turned as rapidly as you say, it is iron. Do you have a pic?
 
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duraleigh

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I would suggest you drop your pH down to 7.0. That significantly speed up the process of getting your pool water blue.

Don't be confused that your polyfill has not captured any iron........you really don't have that much in their and sometimes the polyfill doesn't seem to work, anyway. I have no idea why.

If dropping the pH to 7.0 doesn't get you a blue pool in maybe 48 hours, I would let it drift back up to that perfect 7.4

Your pool will eventually turn back to blue on it's own as the iron moves back into soluble form.
 

duraleigh

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Yeah that's it. I mixed your thread up with another, sorry.

You use it by stuffing the polyfill down into your skimmers. The water passes through it but hopefully the tiny, rust colored particles of iron get trapped and hasten the "back to blue" of your water. I think the pH to 7.0 will work the best but try both if you like.
 

Ron55

Active member
Jun 23, 2013
34
Long Island, NY
So I ordered the polyfill and while waiting for it to arrive the pool went back to blue. I'd say it took several days and besides waiting I didn't really do anything to hasten the process. I left the PH at 7.4 and I had slammed it needlessly and by the time the TC came back to normal levels it was blue.

Any ideas on what caused the iron to come out of solution so I can prevent a reoccurrence?

Thanks for the help.

Blue.jpg
 
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duraleigh

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pH. When you add a large dose of chlorine there is a very temporary surge in pH.......but it is long enough to cause the iron to come out of solution.

Adding the chlorine in multiple small doses will help and keeping sequestrant in your pool will help. Finding a resource for iron-free water helps the most!!