Stains on my steps

[DrThop]

Moved from here.

Funny to see this post, I have the same issue, and only in the steps of my pool and in the shallow end. see the pictures attached. It seems that brushing helps but i have to do a lot of it to get get the spots from black to gray.

today's water results were:
PH 7.5
FC 6
CC 0.5
TC 6.5
CH 125 (it is low)
TA 100
CYA 30

The pool is crystal clear today

Any help will be appreciated.

 

[Texas Splash]

Those areas on the steps, are they pitted? Can't quite tell from the pic. What is the age of this pool or whne it was last re-placstered? You noted the water is crystal today. Has it been crystal clear always, or have you had any issues with clarity or algae recently? The stainings I see almost appear to be organic and embeded which would explain why you see a small change at first when brushed as the chlorine is then able to penetrate the surfece and get to the root of the algae.

 

[DrThop]

Thanks for the reply, yes the areas on the steps are mostly pitted. I don't know how old the pool is, I bought the house 5 yrs ago, and I knew the pool will need to be replastered eventually, I'm just hoping is not this year, but there are some areas where the cement below has been exposed and I used tile repair mortar to patch it up.

The water is crystal clear if I keep a close eye on the PH which tends to climb fairly quickly. but in the last week I have seen more algae growth, requiring constant brushing. maybe I need to SLAM? Also the filter has required constant cleaning (I cleaned it about 10 days ago and the pressure is high again today)

I am not sure if the low CH has anything to do with it... your help is appreciated.