Perimeter Stain

[Pam and Jim]

I have a brownish yellow stain around the perimeter of my pool.
40,000 gallon
vinyl liner - L shape
about 6 years old

There was a faint stain the end of last season- I tried letting the chlorine level drop and added stain remover at end of season- it disappeared
Same stain early this seaon- tried the same thing and the stain went away
Now a few weeks later it is back and worse then ever.

I am not sure if it is metals - in reading the posts I think it may be and I need to try to suspend it??

I was told at the pool store(I know that is a no no so that is why I am asking here) That it is metal because this season about 2 days after using stain remover my water showed high for copper. They said that it takes a week for it to work its way out of the water?
Then when the stain reappeared- it showed no metals at all when tested- They said the metals were no longer showing in the test because they were not in my water- but back in my liner

Is this so?

I have always kept my alkalinity- PH and chlorine in correct ranges
Last year I found this site and switched to chorline- especially for shocking because it does not cloud - so nice

This is driving me crazy- and I find it hard to keep my chlorine level high- it keeps dropping but CYA is good.

Any ideas on who to listen to- what to read- or what else to test?

Thank you for any help that you can give me.

[mbar]

Do you know where the copper is coming from? The reason your stain came back after the stain treatment is because you didn't put in a sequestering agent to keep the metals in suspension. If the metals go back into the water, they need the sequestering agent to hold them in the water, if there isn't enough of it, the high chlorine levels will react with the metal and they will fall out of suspension and land on the surface of the pool. I asked where the metals came from, because copper is in a lot of the chemicals you buy at the pool store now - even in a lot of trchlor pucks. If you think the metals are coming in from your fill water, then you will always have to make sure that you have enough of a sequestering agent in your water. I hope this helps, feel free to ask any questions you may have.

[Pam and Jim]

Thank you for your help.
I will check my tablets- I do use tablets in the chlorinator
I use baking soda to raise the Alk and Soda ash to raise the PH.
Shock with bleach.
I did put in a chemical called Bug out-
Will copper be listed on the bottle- or will it be listed as some other name?

Do you know if the copper could be leaching from an old hose- or somewhere in the filter- any ideas how to check them? How can I can tell if the copper is coming from our city water?

Any ideas on this will help- and thank you again.

Pam

[mbar]

I am pretty sure the copper would be on the label of "bug out" and the chlorine pucks, Other than that I don't know how to find out where the copper is coming from. I don't know where the metals come from in my pool- my water always test no metals, but I get stains, so I can't help you there. Maybe someone else knows more on finding the cause of it? But I do know that they can be controlled by keeping a sequestering agent in the water, adding the fill water through the filter, and keeping the ph on the low side. Post your chemical numbers (fc, cc, tc, alk, ph, cal,cya) and maybe I can see if anything is off.

[sartail]

Do you have a brand of sequestering agent that you recommend? How do you add fill water through the filter? (I have an above ground pool w/ sand filter.)

[mbar]

I have used metal free, sequasol & Jacks Magic. They are all good. To add the fill water through the filter, you put your hose in the skimmer (with a trichlor puck). The water will hit the puck, and flow right into the filter before it is returned to the pool, so it could help the metal stain the filter instead of the pool. The sequestering agent should keep the metal in suspension - make sure you add at least enough of what the bottle says, because more won't hurt anything, but not enough will leave some metal free to fall onto the liner.