Tarp method in-place water replacement

The only other source would be to check your external plumbing. It is a very commonly made mistake by plumbers to attach cheap galvanized steel pipe nipples to make connections through a wall between brass fittings and brass spigots. I found a number of these in my own home. Whenever galvanized pipe is in contact with brass, the galvanized pipe will corrode due to the formation of a galvanic couple. Grounding is not necessary for the corrosion to happen and pipe tape doesn’t prevent it either. It’s a shortcut that is often used because galvanized pipe comes pre-threaded in various lengths (1”, 3”, etc) so its easy to use. It’s a lazy choice and against good plumbing practice but it gets done all the time. Usually a homeowner finds it when the galvanized finally gives way and there’s a huge leak.

Maybe look at your external plumbing and see if it’s ok.
 
Quick update to say there is no hint of metal stains after replacing the water. It’s been a full month since the water was replaced.

I should have done this years ago. Iron stains started 7 years ago. The past 3 years were the worst. 3 years of having to add Metal Magic weekly only to see the stains return every week.

I had replaced water in the past but in hindsight, I guess I didn’t replace enough water to dilute the iron concentration. Anyway, not claiming victory yet but feeling very optimistic to not have stains after a month without adding any Metal Magic.

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When you were using your SWG, who originally added salt to the pool and what brand were you using ?

it’s very odd that you never located the iron source.
 
When the pool was built the salt was added by the builder. I can’t remember what brand he used but his pool store sold AquaSalt.

Over the years I mostly used AquaSalt but remember using Morton pool salt and maybe even the dreaded Clorox brand once.
 
Carlos, thanks so much for posting all of your experience with the tarp method. I’m giving it a go right now and with the advice in this thread I know I have a fairly good shot at being successful unless I make a mistake. I’ve had so many staining issues in my first year of ownership and I’m determined to get this right before closing up the pool for the long winter season here in CT. I started a new thread (was in The Deep End but a moderator moved it to Water Chemistry) in hopes that my posts can help others, just as yours helped me. Cheers. Would also love to hear from you if your staining issues have remained at bay now a few months later.
 
Dtrav, good luck with it. The metal stains were something I battled for close to 7 years. In hindsight, I should have done it long ago.

The good news is that my liner and fittings are still stain free. If I remember correctly, I did the water replacement after the July 4th weekend so it’s been almost 3 months.

Here are a couple photos showing what it looks like today.
 

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Dtrav, good luck with it. The metal stains were something I battled for close to 7 years. In hindsight, I should have done it long ago.

The good news is that my liner and fittings are still stain free. If I remember correctly, I did the water replacement after the July 4th weekend so it’s been almost 3 months.

Here are a couple photos showing what it looks like today.
Looks great! Thanks for the update. 7 years, geez! I’m so grateful I found this site and your post, I see how I easily could have gone 7 years with trying all the different sequestrants as well as hiring someone and paying a lot of money to probably do a poor job of fixing the issue.
 
Carlos, thanks again. I just finished my water exchange with no hiccups following the advice from this thread. I can't believe the difference in the water color without the copper in it already! Even after having removed the stains, the water was a very obvious green color prior to the exchange, although I thought maybe it was just the way it was supposed to look due to having a white fiberglass pool. And here I was thinking since I have a white rather than a blue liner or whatever bottom that's why it didn't look very blue before...

after AA before exchange.jpegafter exchange.jpeg
 

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Large quantities of pure water will appear to be a light turquoise blue when seen against a white background. Hydrated copper ions (copper aquo-complex) tend to add a blue coloration while iron aquo-complexes are more blue-green. Pool water tends to have very high TDS as well as suspended solids which can also shift the visible coloration. Organic acids like tannins from decaying plant matter tends to add a yellow/brown coloration to water.

Your water looks much better.
 
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