Scale removal/rust

Wake9909

Member
Mar 28, 2020
9
Broken Arrow, OK
Hi, guys! I’m new to being a pool owner, and also new on this forum. I hope I’m posting this in the correct category as I was unsure exactly where this fits. I have hopefully correctly updated my signature with all my necessary pool specs. Let me know if you need any further information.

Anyway, while trying to get our chemistry balanced (mainly pH), a large amount of scale has shown up on our pool tile. Most of it came off with diluted muriatic acid and a soft bristle brush. On the stubborn areas, my husband had to use a wire brush to remove the scale. This was a couple days ago. Today, I’m noticing some small rust-colored spots on the plaster below where he used the wire brush (see attached pic for example). 1. Is there any way to safely remove those spots, or are we now just permanently stuck with them?, and 2. What other method can we use going forward to get rid of those stubborn areas?

Thanks in advance for your help!
 

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mknauss

Mod Squad
TFP Expert
Bronze Supporter
May 3, 2014
29,483
Laughlin, NV
A wire brush is, metal. It shed some small pieces of metal and they are rusting. Best to not use a wire brush around the pool.

Use some Vitamin C tablets crushed up in a sock and put on the spots. They should go away after a few minutes.
 
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Wake9909

Member
Mar 28, 2020
9
Broken Arrow, OK
Thank you! Yeah, we won’t be doing that again. Live and learn. I’m just happy there’s a solution to fix it! Do you have any recommendations as to how to remove the stubborn scale that doesn’t involve a wire brush? ? Thanks again in advance!
 

mknauss

Mod Squad
TFP Expert
Bronze Supporter
May 3, 2014
29,483
Laughlin, NV
Some use pumice stone. Where is the scale occurring? If you have high CH fill water, it is likely you will always have some evaporite scale on your waterline.
 
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Wake9909

Member
Mar 28, 2020
9
Broken Arrow, OK
As far as minimizing the scale buildup, can you post or share on Poolmath your water chemistry test results?
Yes, I’m still trying to figure this all out, but I’ve been keeping a notebook with all the chemistry results in it. I’m about to check the pH and chlorine again, but as of 4-5-20, the water temp was 57 degrees, the salt level was 3,000, the pH was 7.8 (down from 8.2 the day before...because we added a quart of muriatic acid), chlorine level was right around 6ppm.

In addition to pH and free Chlorine level, I test Total alkalinity (mathematically adjusted for CYA), calcium hardness and sometimes CYA on Saturday every week. On 4-4-20, calcium hardness was 250 ppm, TA was 83 (adjusted), and CYA was 46(ish) ppm. pH was 8.2 units that day. Our pool is a brand new salt water pool and we are almost always on the basic side of pH. It seems difficult to get the pH acidic enough right now. We’re learning as we go. Very thankful for this forum.

I want to start using pool math eventually once I can get this all under control.
 

mknauss

Mod Squad
TFP Expert
Bronze Supporter
May 3, 2014
29,483
Laughlin, NV
You have the Poolmath app. Enter your test data. Remember to NOT adjust your TA for CYA. Poolmath manages that.

Also, you can not measure a CYA of 46. Round up to the next highest value.

I suspect your TA is quite high and that pushes your pH up. Keep lowering your pH to 7.4 when it gets to 8. That will lower your TA.
 
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Wake9909

Member
Mar 28, 2020
9
Broken Arrow, OK
You have the Poolmath app. Enter your test data. Remember to NOT adjust your TA for CYA. Poolmath manages that.

Also, you can not measure a CYA of 46. Round up to the next highest value.

I suspect your TA is quite high and that pushes your pH up. Keep lowering your pH to 7.4 when it gets to 8. That will lower your TA.
Thank you. That’s actually what we’re working on doing right now (lowering the pH). Our Taylor test kit came with a wheel thing that shows us overall how balanced our pool is. The goal is to get it down to “0.” With all other values remaining constant, if we adjust the pH to 7.6, it gets us very near to “0.” If that makes sense. ☺