Algae or something else?


New member
May 10, 2008
Two years ago, when opening our inground vinyl pool, we noticed a depression on the shallow end of the pool. We called our local pool company who diagnosed this as a leak and patched it (glued about an 8 inch diameter piece of vinyl over the leak. Last year when we opened the pool, we noticed a rather large black stain around the patch, but we were not able to remove it through scrubbing. This year the stain has gotten bigger and is quite an eyesore. Is this some form of algae, some reaction to the glue or something else?


Rob G.


LifeTime Supporter
Platinum Supporter
TFP Expert
May 7, 2007
Silver Spring, MD
The mold is presumably on the other side of the liner, so no amount of scrubbing or water treatment will take care of it. If it is indeed on the other side of the liner the only practical treatment starts with replacing the liner, so you may need to live with it for a while.


Well-known member
May 20, 2007
Houston, Tx
What about draining the water down some, and then slicing the liner open in the area where the mold is, take some bleach to it, to kill off the mold, and then re-patch what you just cut away?
You probably can but YOU ARE PUTTING ANOTHER WEAK SPOT IN THE LINER!!!! Sorry for shouting but I wanted to get your attention on that one. Patches are NEVER going to be as strong as an uncut liner and have been known to fail and start leaking again.