brown stain around bottom perimeter


New member
Jun 10, 2010
I have a brown stain around some of the bottom perimeter where the sides meet the bottom of my inground pool. I tried the vitamin c tabs and that had no effect. I tried super shocking which had no effect. Pump runs overnight unless we are swimming. In the morning the stain is not noticeable but there. Once day begins and sun comes up over the house the stains really pop out. The stain reminds me of a water stain on the ceiling from a roof leak. Current readings are FC=2, PH=6.4, TA=80, CH=100, CYA is pretty much 0. But, adjusting chemicals over the last couple weeks has had no effect. We do use a minimax 100 heater. Can't make determination if organic, metal, or something under liner. Stain appeared last season, but not in any way as prolific as it is now and didn't last long. It wasnt there when we first opened pool this season. Could it have been caused by heavy rain that put water to and over top of liner? Turning on the heater? Warmer temps outside? And how can I get rid of it? thanks. K. Brodie. Staunton, IL


LifeTime Supporter
Jul 29, 2009
I would get your pH up (at least 7.2), and get some CYA in the pool first...

Then do an over night chlorine loss test.

If you are loosing chlorine overnight, shock until you are no longer loosing it over night.

I have a similar sounding stain this year. I dropped a puck on in and in about 2 hours, the stain faded where the puck was. Over the last few weeks, it has been fading by keeping my chlorine levels a tad higher. With vinyl... don't know if that's a good idea or not.

I'd be happy to provide specifics if you would like.


TFP Expert
LifeTime Supporter
Feb 23, 2008
Denton, TX
If the vitamin C test didn't work, then it is probably an organic stain of some kind. Like you said though, it would be tough to determine if the stain is on the inside or the outside. Have you tried placing a chlorine tablet on it for a few minutes to see if it lightens? If it does, then it is on the water side of the liner. If it doesn't then it is probably on the outside of the liner but is showing through somehow.

I agree with waskydiver that you really need to get that pH up quickly and get some CYA in your pool. Without the CYA in there, it would make it tough to shock since the chlorine won't stick around for more than an hour or so.


TFP Expert
LifeTime Supporter
In The Industry
May 20, 2007
SWSuburban Chicago, IL
I third? :) the recommendation to raise your PH and adjust the CYA.

That sounds exactly like organic staining that I used to get. Proper FC levels will make the staining fade over time.

Other Threads of Interest