a few yellow brown spots on the walls getting little sun

[engrav]

Hi
Am back, all stuff previously discussed underway. FC now 8 and will gradually exchange water to lower CY from 80. Rainbow set to zero. Cheap generic bleach did raise the pH now fixed with acid.

New question about algae.

Brushed today. On the sunless walls found a few small areas (few inches in diameter) of yellow brown color that brushed off easily and made a vague cloud and was then gone. Water is very clear, can see all the plaster defects. Is this algae? Yes No.

If yes, should this never happen? Or is this how it is from time to time and you just brush off (so to speak) and move on?

Thank you.

 

[marty]

Happens to my pool when I have high pH, 7.5+. If you can brush off then its algae, when you drain some water to lower cya, tie a floater to area affected so it gets constant CL. and if you can put your liquid CL in that area from now on.

 

[duraleigh]

What you describe is likely mustard algae. In a properly maintained pool, it should not occur.

Brushing it up into the chlorinated water often works well but is temporary.

It is still consuming some of your chlorine and your pool, if you elevate your chlorine to adequate levels to prevent it, will look better and perform better for you if you maintain higher chlorine levels.

 

[Butterfly]

Yep, based on the history, it is most likely mustard algae. You should follow the directions in Pool School on how to get rid of it.

To help get a head start, if you have any underwater light niches, open and clean them out and expose them to the SLAM levels.

 

[engrav]

Yep, based on the history, it is most likely mustard algae. You should follow the directions in Pool School on how to get rid of it.

To help get a head start, if you have any underwater light niches, open and clean them out and expose them to the SLAM levels.

thanks to both, am on it

by the way, patches have not returned this AM
also FC is 8-10 range (CY is 80 from previous discussions)

 

[engrav]

derivative query please

S wall which does not get much sun has some yellow stains up near the waterline
were there when we bought this in 2011

if yellow algae is on a wall for a long time, then you kill the algae, does the yellow color remain?
or is that yellow stain something else?

thank you