Metal Stains or Scaling?

[mikesig83]

Hello TFP members,

My original post may have been in the wrong thread.

Recently I’ve been noticing what looks like metal stains getting bigger on my pool floors. I can’t tell if it is calcium scaling or some type of metal stain. It is very strange thing because when I look at the bottom of the pool when it is sunny outside, it looks absolutely perfect. I cannot see any stains. When it is cloudy or starting to get dark, I can clearly see the stains. I’d say it covers roughly half to three quarters of the surface. It seems to be getting worse, too. Anyone have any idea on what it could be? It’s a yellowish type stain and has a lot of coverage (meaning, it is not spotty). It does not come off by scrubbing. I can try to post some pics if I can catch it in the right light (hard to do here with the blazing TX sun).

In February, I tried to do an ascorbic acid treatment (thinking it was a metal stain). It did not work at all. It says to put the filter on circulate. What does that mean? When I went to clean my filter (cartridge), I noticed a lot of heavy white stuff in there. Almost like wet toothpaste. It took me forever to clean. I’m wondering if I need to take out the filter cartridge when doing the ascorbic treatment
.
Here is my latest reading:

FC: 2
CC: 0
pH: 7.2
TA: 120
CH: 320
CYA: 50
Temp: 85

Appreciate any insight you all may have.

Thanks,
Mike

 

[Bama Rambler]

Did you try holding a trichlor puck on it and see of that helped?

 

[mikesig83]

Did you try holding a trichlor puck on it and see of that helped?

No, I have not tried that. Is that to check if it’s algae?

 

[Bama Rambler]

It's to check to see if it's organic since it didn't appear to be metals (AA didn't work).

 

[mikesig83]

I doubt it, but I will try it tonight. I've scrubbed it before with a hand brush and nothing happened. It's very strange. If you or anyone else has any ideas, please let me know. Thanks, Mike

 

[257WbyMag]

Scrubbing it only tells you that it is a stain. It doesn't tell you the type of stain. A stain is typically organic (some sort of stain resulting from a life form) or metal. If the chlorine tablet lightens the stain, then chlorine will eventually eliminate it. If the tablet doesn't change the stain, try scratching a vitamin C tablet on it. If the stain lightens from the vitamin C tablet, its a metal stain and you will need to use a sequestrant.

 

[mikesig83]

Scrubbing it only tells you that it is a stain. It doesn't tell you the type of stain. A stain is typically organic (some sort of stain resulting from a life form) or metal. If the chlorine tablet lightens the stain, then chlorine will eventually eliminate it. If the tablet doesn't change the stain, try scratching a vitamin C tablet on it. If the stain lightens from the vitamin C tablet, its a metal stain and you will need to use a sequestrant.

Thanks. Seems like you live in the same town as me. Does our fill water have metals in it that we have to worry about? Also, what if neither the chlorine or the vit C tablet lighten it? Does that mean its scaling?

-Mike

 

[257WbyMag]

Well, aside from calcium, we have no metals. The CH in our fill water can get high though. Especially in the summer. If it feels rough or raised, it's going to be calcium. What is your CH?

 

[mikesig83]

Last reading last night was 320. I noticed my pH was high all winter, FWIW. Constantly using MA to lower it and TA. My gut is telling me it's a scaling issue.

 

[257WbyMag]

Last reading last night was 320. I noticed my pH was high all winter, FWIW. Constantly using MA to lower it and TA. My gut is telling me it's a scaling issue.

You are probably correct. We live in an area where scrutinizing CH levels is important. We have hot summers with a lot of evaporation and subsequent water replacement. Because of this, it doesn't take long for CH to rise and start depositing itself on surfaces. We don't have it as bad as the desert SW does, but we can't let it go either. I add acid almost every day and I stay on top of it during the winter too.

 

[mikesig83]

Do you use acid to keep ph down for the csi index.? Ch at 320 isn't too bad right? I guess it could go higher...

 

[JohnN]

Yes, muriatic acid to lower pH. A CH of 320 is good. Some people have CH of over 800, sometimes up to 1000.

 

[mikesig83]

Is the only fix to calcium scaling a full drain and acid wash? Is there anything I can do to help prevent future stains?

 

[JohnN]

Maintaining a slightly negative CSI can, over years, dissolve scaling. I will let someone with more experience elaborate on that. To prevent scaling, you have to keep your CSI close to zero, and never let it get above +.6. Putting your numbers into the pool calculator will tell you your CSI.

 

[Bama Rambler]

Take a read through Richard320's threads and you'll see how he has done it.

 

[mikesig83]

Take a read through Richard320's threads and you'll see how he has done it.

Seems like keeping a low pH and lower TA (thus lower CSI, keeping it under 0) at all times will help remove the stains over time. I will give that a shot. Not sure how much "scrubbing" with a wire brush I can do at 6 feet underwater. I hope just keeping low pH and TA will help stop further scaling and slowly remove the scale deposits that are already there. If anyone else has suggestions, let me know!

Thanks,
Mike