Concrete floor and walls turned blue while pool was closed for Winter

rileyswim7

Member
May 2, 2020
5
Centreville, MD
I have a 40,000 salt water pool. On opening the concrete floor and walls all have a blue stain (normally white). I just had the water tested and the chlorine level is 18, hardness is 166 ph 7.9. Prior to this I used magic jack stain test and it appeared that the copper stain kit with shock removed the stain.

I just bought Metal-out plus and poured it in the deep end and will wait until tomorrow to see if the stain is gone. Meanwhile, Why would my chlorine be so high, I have my salt cell generator set at 50% and just turned it down to 10%. How can I lower the chlorine without draining the pool. I am so confused! Thanks in advance for any help!
 

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rileyswim7

Member
May 2, 2020
5
Centreville, MD
I have a 40,000 salt water pool. On opening the concrete floor and walls all have a blue stain (normally white). I just had the water tested and the chlorine level is 18, hardness is 166 ph 7.9. Prior to this I used magic jack stain test and it appeared that the copper stain kit with shock removed the stain.

I just bought Metal-out plus and poured it in the deep end and will wait until tomorrow to see if the stain is gone. Meanwhile, Why would my chlorine be so high, I have my salt cell generator set at 50% and just turned it down to 10%. How can I lower the chlorine without draining the pool. I am so confused! Thanks in advance for any help!
 

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Texas Splash

Mod Squad
TFP Expert
LifeTime Supporter
It would appear that you have built-up an elevated FC level based on the pump run time combined with the SWG output setting. Add to that chilly water and the FC doesn't burn-off as fast. An FC of 18 normally isn't a big problem unless you have metals in the water. If you have been using a pool service or pool store chemicals frequently (like algaecides) there's the problem. Sounds like the Magic Jack's confirmed it. Copper stains can be quite challenging to remove.

What to do now? We would recommend #1 testing your own water. #2 would be to stay away from the pool store and/or pool service if you are using one. Take 100% control of your own testing and adding chemicals as required. It's really not that difficult if you have the right test kit. We recommend to everyone on the forum to obtain a TF-100 (link below in my signature) or a Taylor K--2006C. Either of those are dependable and easy to use.

The only way to remove copper from the water is to exchange the water. Even if you use a sequestrant, it's just in a liquid state. It never leaves until you change enough water to make the copper level go down. For right now, let the FC fall a bit, but not too low or you risk getting algae. If you know your CYA level, go to the FC/CYA Chart to see what the FC should be. Also make sure to keep the pH from getting too high. A high pH makes the staining worse. Try lowering the pH to about 7.5 for now.

If you obtain one of those test kit, post a full set of test numbers and we assist more.

 
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rileyswim7

Member
May 2, 2020
5
Centreville, MD
It would appear that you have built-up an elevated FC level based on the pump run time combined with the SWG output setting. Add to that chilly water and the FC doesn't burn-off as fast. An FC of 18 normally isn't a big problem unless you have metals in the water. If you have been using a pool service or pool store chemicals frequently (like algaecides) there's the problem. Sounds like the Magic Jack's confirmed it. Copper stains can be quite challenging to remove.

What to do now? We would recommend #1 testing your own water. #2 would be to stay away from the pool store and/or pool service if you are using one. Take 100% control of your own testing and adding chemicals as required. It's really not that difficult if you have the right test kit. We recommend to everyone on the forum to obtain a TF-100 (link below in my signature) or a Taylor K--2006C. Either of those are dependable and easy to use.

The only way to remove copper from the water is to exchange the water. Even if you use a sequestrant, it's just in a liquid state. It never leaves until you change enough water to make the copper level go down. For right now, let the FC fall a bit, but not too low or you risk getting algae. If you know your CYA level, go to the FC/CYA Chart to see what the FC should be. Also make sure to keep the pH from getting too high. A high pH makes the staining worse. Try lowering the pH to about 7.5 for now.

If you obtain one of those test kit, post a full set of test numbers and we assist more.

Thank you so much! I'll order a kit tonight and post values as soon as I get it. I appreciate your quick response!
 
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IceShadow

Gold Supporter
TFP Guide
Jun 8, 2019
2,177
Milwaukee, WI
Never heard of blue staining yet, but I could help with the chem balance. Can you fill out your signature, and let us know how you test chem levels?
 

aeh0603

Well-known member
Apr 6, 2016
348
San Diego, CA
My hunch is metal staining. I think copper can cause blue stains. I have more experience with iron staining though. When the concentration of metals gets too high in your water, in your case this is likely from copper containing pool products like xtra-blue products or algacides, high levels of FC or pH can cause the metal to oxidize and either turn your water a different color, or deposit on your pool surface in the form of a stain.

If you can tell us how you are testing your water and post a full set of test results we can help with the water balance.

FC - 18 (we can't know if this is too high without knowing your CYA/stabilizer level)
CC -
pH - 7.9
TA -
CH - 166 (is this from a pool store test?)
CYA -