Brown spots on Pebble Tec

propjetprop

Gold Supporter
Jan 5, 2018
103
Douglasville Georgia
So the pool is about 1 year old now. I have been maintaining to TFP standards since the beginning. I noticed at the end of last summer there was one brown spot on the bottom of the pool that would not sweep away. I did not do anything about it. Now they are all over the pool. These brown stains on the pebble tec. What started as one brown stain, is now many. I brush several times a week, and these stains are not going anywhere. The brush does not phase them. ... Here are my numbers:

FC ..........10 ( I just turned the SWG down from 40% to 20% to lower this to 5)
CC............ 0
CYA.......... 60
CH............ 100
TA.............. 80
PH............. 8 + (my gauge only goes up to 8) I have trouble keeping the PH below bright pink 8.0.. I use Muriatic Acid to lower when needed.

Any recommendations on how to understand what these stains are and how to treat them? Or at least get them to stop spreading?

PS.. I do not have any leaves in the pool. There are no trees in my yard, so I know it is not leaf stains.
 

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pooldv

TFP Expert
Platinum Supporter
LifeTime Supporter
Moderator Emeritus
Aug 10, 2012
25,412
FL panhandle
Keeping your TA closer to 60 will help you keep your pH at 7.8. Let us know how the stain diagnosis goes and we can help solve it.
 
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JoyfulNoise

TFP Expert
Platinum Supporter
May 23, 2015
17,363
Tucson, AZ
Crush up Vitamin C tablets in a nylon and place it on one of that stains for 5-10mins. See if it lightens or removes the brown stain. Report back.
 

propjetprop

Gold Supporter
Jan 5, 2018
103
Douglasville Georgia
Thanks for all the replies!

I dont think it could be fertalizer as I do not fertalize my yard... I have the PH lowered to 7.2 and the TA lowered to 60.... I am working on figuring out an aereator system to bring the ph back up while keeping the TA at around 60 and will continue to brush. I will try the vitamin c trick and report back.!

Thanks
 

umpalumpajay

Well-known member
Dec 23, 2014
160
West Hills, CA
I have this exact problem as well, 3 years in using TFP the whole time, brown stains on pebble. I need to try the vitamin c thing. Mine looks like rust almost. I’m guessing I wasn’t keeping my ph low enough. I’d let it rise up to high 7s and 8 before knocking it down. Trying to stay closer to 7.4 and just bumped up my alkalinity to 70 from 40. Your ph is way too high so maybe keep up with keeping it lower.
 

JoyfulNoise

TFP Expert
Platinum Supporter
May 23, 2015
17,363
Tucson, AZ
Typically spot-stains line those are not from metals in the water. Metal contamination in the water would cause broad swaths of staining across large areas of the pool. Spots like that, if they are metal stains, come from rebar or rebar ties poking through the gunite OR a contaminant that got incorporated into the plaster because the surface was not properly cleaned and prep’d prior to plaster application. In those circumstances, you typically need to chip-out the plaster in those areas to remove the contaminant or grind out any rebar that’s too close to the surface....or just live with it.
 

pooldv

TFP Expert
Platinum Supporter
LifeTime Supporter
Moderator Emeritus
Aug 10, 2012
25,412
FL panhandle
I have heard of a few cases where the abalone shells werent completely cleaned and they caused some issues with spots as they continued to decompose. It will ultimately resolve itself with chlorine and brushing.
 

Dram414

Member
Sep 24, 2019
11
Texas
So the pool is about 1 year old now. I have been maintaining to TFP standards since the beginning. I noticed at the end of last summer there was one brown spot on the bottom of the pool that would not sweep away. I did not do anything about it. Now they are all over the pool. These brown stains on the pebble tec. What started as one brown stain, is now many. I brush several times a week, and these stains are not going anywhere. The brush does not phase them. ... Here are my numbers:

FC ..........10 ( I just turned the SWG down from 40% to 20% to lower this to 5)
CC............ 0
CYA.......... 60
CH............ 100
TA.............. 80
PH............. 8 + (my gauge only goes up to 8) I have trouble keeping the PH below bright pink 8.0.. I use Muriatic Acid to lower when needed.

Any recommendations on how to understand what these stains are and how to treat them? Or at least get them to stop spreading?

PS.. I do not have any leaves in the pool. There are no trees in my yard, so I know it is not leaf stains.
I have the exact same problem in a 2 month old pool. Very frustrating. I haven’t figured it out yet, the pool looks like it’s dirty all the time. If you figure it out let me know. I have a mini pebble aqua cool with some abalone added
 

Jimmie48

Well-known member
Dec 13, 2019
141
Frisco, TX
I am going to bump this thread because I have seen some small brown stains in my plaster similar to this. I have squirted some muratic acid under water over them and they seem to go away but one section seems to be coming back a few weeks later. My pool is balanced well, I keep knocking down ph now that I have gone to liquid after my cya got up to 30's and keep the cl level in the 5's pretty regularly. If anyone has any ideas what this could be let me know. I know my shell was cleaned well and there were no ties near the surface.
 

Dirk

Gold Supporter
TFP Guide
Nov 12, 2017
7,152
Central California
Matt's answer (in post #9) is likely the correct one, though maybe not about the origin of the source of the stain. I had one of those spots. I just found another. Newish pebble. The installer knew exactly what it was, didn't question me about it or my pool or my water, just sent a guy out who jumped in and fixed it. So quick I didn't get to watch what he did. IMO, rebar is possible, but not likely. That wasn't it in my pool. It wasn't the water. My best guess, it's some sort of metal that got into the pebble raw material, and is rusting from the inside out. Or as Matt suggested, was leftover from the gunite prep. Which is why chemical treatments or water adjustments or brushing isn't making them go away. It's not on the surface, it's embedded. It wouldn't take much. They're harvesting these pebbles from nature somehow, right? Surely a sliver of iron, or a stone with iron in it, get's into the mix now and then (and gets past whatever they must do to mitigate that).

Anywho, my five-year warranty covered this issue. The fix was no cost to me. And as I said, they knew exactly how to fix it, and the same spot never came back. Don't apply "home remedies" or whack out your water such that you void your pebble's warranty. Call the installer first and get him to honor the warranty.

If you're out of warranty, then call them anyway and pay them for the fix, and to teach you how to do it. I'm going to watch the guy closely when he fixes this second spot, so I can do it myself after my five years are up.
 
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Dirk

Gold Supporter
TFP Guide
Nov 12, 2017
7,152
Central California
I have squirted some muratic acid under water over them and they seem to go away
I'd caution you about doing that. (Though I'm no expert.) A high enough concentration of Muriatic Acid will eat your plaster doing that. Which might be why the stain goes away, as the stain is floating away with the plaster you've removed. If the metal flake floats off with it, then that's a solution, I guess, as long as the resulting pit and/or etching is not noticeable, or is acceptable to you. But for the spots that are coming back, that's the flake embedded more deeply continuing to leech rust. If you keep squirting it enough to finally reach the metal, you could end up with a nice-sized divot, or a large etched area, or both. Point is... Muriatic Acid doesn't magically attack stains and leave surrounding plaster alone. It's destroying plaster, and maybe or maybe not the stain itself in the process.
 
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Jimmie48

Well-known member
Dec 13, 2019
141
Frisco, TX
I looked on TFP's posts and many use some acid to remove metal stains which it looks like it was. The acid literally sits there for a second and is underwater which dilutes it quickly. Really no difference than adding it to your pool albeit this is much smaller quantity and basically like a local acid wash. If it keeps coming back I will contact the PB as my plaster is less than 2 months old...thanks all!