Another stain question

buddywiser

LifeTime Supporter
May 23, 2007
103
Morgantown, WV
I've been treating my vinyl liner pool for metal stains for a couple years now. I use Pool Magnet Plus on a regular basis and it works great. I've had my water tested a few times and both times it's tested negative for both iron and
copper. A vitamin C tablet clears the stain up instantly when it's present. What other metals could I test for?

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JasonLion

TFP Expert
Platinum Supporter
LifeTime Supporter
May 7, 2007
37,879
Silver Spring, MD
It could be manganese, though I rather doubt it. Most likely it is iron and the metal test was simply wrong. What color are the stains when you have them? If they are yellow/brown/rust colored then it is certainly iron.
 

JamesW

TFP Expert
Mar 2, 2011
18,419
It is not unusual for a metal test to show no measurable metals when there are metal stains. As Jason said, it is most likely iron. If most of the iron has precipitated as a stain, then there won't be enough left in the water to register on the test.
 

buddywiser

LifeTime Supporter
May 23, 2007
103
Morgantown, WV
I've had the CuLator in for about 4 days now. No changes to the color yet. Pool is sparkling clear, so the metals should be going through the system and not stuck on the liner. One thing I'd like to understand better is, How do the metals get in the water in the first place? I have a heater and I think that contributes, but am I adding them in with the chemicals that I use? Besides BBB, I do use a cheap algaecide from Lowes occasionally.
 

chem geek

TFP Expert
LifeTime Supporter
Mar 28, 2007
12,083
San Rafael, CA USA
Metals can come from the fill water, such as iron in well water. Metal ions can come in some algaecides, especially copper, and is even found in some Trichlor pucks/tabs. It is unlikely to come from your heater unless your pH got very low or you frequently had Trichlor pucks in your skimmer (they are very acidic) or added acid to the skimmer (a definite no-no).

When the CuLator works, it is slow and will take more than just a few days -- more like a month or more. We still don't have enough reports to be definitive about it effectiveness, though at this point it's better than 50/50.
 

buddywiser

LifeTime Supporter
May 23, 2007
103
Morgantown, WV
Been dealing with the same staining issue for a few years now. Entire vinyl liner gets a dull yellowish stain. Iron and Calcium tests always come back negative. I throw in a quart of Pool Magnet Plus and the next day, the liner is sparkling clear. 3 weeks later, the stain begins to return. Goes from hardly noticeable to just plain ugly.

I was wondering if the age of the liner could play a role in how susceptible it is to staining. This one is nearing its end of life (14-15 years old). Any thoughts on that?
 

JasonLion

TFP Expert
Platinum Supporter
LifeTime Supporter
May 7, 2007
37,879
Silver Spring, MD
Pool Magnet Plus is a sequestrant. Sequestrant breaks down over time. You need to add more at regular intervals to keep the metals held in solution and prevent them from redepositing as stains.

The age of the liner wouldn't have anything to do with it.