Brown edge with blue green center

[nate086]

I have spots on the bottom of my that have a brownish color edge and blue green center. The water has always remained clear. I have tried the stain test kits and nothing seems to help. I have balanced the pool chemistry but the spots still remain and brushing has no effect.

[Teapot1]

Sounds like cyanobacteria, incorrectly named black algae by the pool industry. It has the tough outer shell that protects the inside so some abrasive to remove that then a chlorine tablet directly onto the spot may help. Chlorine dioxide is more effective but harder to use

[Mammaw Pam]

I don't have a clue about balancing all the chemicals in the pool (hubby does that)....BUT, I can tell you a simple fix to get those stains off your pool liner and steps.....VITAMIN C tablets.....Just get you a bottle (I use cheap brand), pour some in an old sock and touch it to the stain...It comes right off.

[Teapot1]

vitamin C tablets.....Just get you a bottle (I use cheap brand), pour some in an old sock and touch it to the stain...It comes right off.

That puts the iron, if it is iron back into solution it doesn't get rid of the issue so when conditions are right (pH a bit high and fresh dose of oxidising chlorine) the staining re appears, may not be in the same place. Actually removing the metals requires further treatment and sequestrant is not a cure as chlorine burns out the sequestrant over a few weeks so you have to buy more which becomes an endless cycle with the only winner being the pool shop. You can remove the metals permanently but how did they get in there in the first place is the main question.