Brushed a Stain ... Did I make it worse?

[sigmond]

My pool is 2 years old (10,000 gal chlorine with Aqua White StoneScapes mini pebble finish)

I noticed a couple of weeks ago 2 small black dots on the pebble finish (~1/8") that were surrounded by a faint brown circle (~1.25"). The pebble finish has some natural black pebbles, but these spots stood out (see pic #1). My first thought was the start of Black Algae. But I have never dealt with any algae problem with my pool, so I could not be sure.

I immediately scrubbed with my standard 50/50 brush. It had no affect. I got distracted with other things. After 2 weeks went by, there had been no change for the worse. My next thought was that it may be a stain from some organic matter.

I then purchased a small stainless brush - and scrubbed the spots. When the water settled, I noticed that the spots where I scrubbed are now darker - as if I may have damaged the finish (see pic #2)

I then brushed with my 50/50 brush, to try and blend it in ... to no affect. From my limited research, I thought that using a SS brush was ok on a pebble finish.

Q: Did I permanently damage the finish?
Q: If not, what can I do to correct it?

Please, advise.

>>>>> CHEM MEASURES
FC = 4.2 (I use LC - and this in the min)
TC = 4.4
PH = 7.7
TA = 72
CH = 255
CYA = 53

 

[YippeeSkippy]

Sigmond, welcome to TFP. Were those test done by you?? If so, which test kit did you use??

1)When the black spot first appeared, did you put any chemical directly on it?
2)How do you chlorinate your pool?
3)What other chemicals do you use? Tell me everything, even one time used chemicals.
4) How many spots are there??

I'm going to ask a cement expert here what he thinks. In the meantime please don't do anything more until we hear from him, ok?

@onBalance , does this look like a chemical issue, overbrushing issue, hydration issue or something I can't figure out???? Thank you.

Maddie

 

[sigmond]

Sigmond, welcome to TFP. Were those test done by you?? If so, which test kit did you use??

1)When the black spot first appeared, did you put any chemical directly on it?
2)How do you chlorinate your pool?
3)What other chemicals do you use? Tell me everything, even one time used chemicals.
4) How many spots are there??

I'm going to ask a cement expert here what he thinks. In the meantime please don't do anything more until we hear from him, ok?

@onBalance , does this look like a chemical issue, overbrushing issue, hydration issue or something I can't figure out???? Thank you.

Maddie

Q: Were those test done by you??
A: Yes

Q: If so, which test kit did you use??
A: ColorQ Pro 7 (2056), Taylor K2005.
I use ColorQ the most. I calibrate each tube separately - and it is super accurate. Once a month, I cross-check the measures with the Taylor kit.

1) When the black spot first appeared, did you put any chemical directly on it?
A: No

2) How do you chlorinate your pool?
A: Liquid Chlorine

3) What other chemicals do you use? Tell me everything, even one time used chemicals.
A: Just the standards ... LC, Muriatic, CYA. I am planning to use PR-10,000 soon to reduce Phosphate (Level is at 848 currently). I did recently add Calcium (180 to 255) and CYA (30 to 53).

4) How many spots are there??
A: Only the 2 small ones

 

[JamesW]

Probably a piece of steel in the plaster.

See if a strong magnet will stick to the spot.

 

[onBalance]

Sigmond, I think your second thought is the correct diagnosis; that it is some kind of organic matter (leaves, etc.) that got into the plaster during the troweling process. After some time, organic matter can decay and discolor the plaster somewhat. I am not aware of effective ways to remove that discoloration.

 

[sigmond]

Q: Any ideas on how to fix the damage that I caused by scrubbing too hard?

The dark spots that I created are 10x worse than the original problem

 

[JamesW]

See if a strong magnet will stick to the spot.

Put some vitamin C on the stain and see if it removes the stain.

 

[sigmond]

See if a strong magnet will stick to the spot.

Put some vitamin C on the stain and see if it removes the stain.

Vitamin C made the stain disappear!

 

[JamesW]

See if a strong magnet will stick to the spot.