Discoloration in shallow end, wonn't brush

[flipr]

Just started noticing this stain on the pebble, started in the past 6 weeks or so, only in shallow end, but there are 'trails' heading to deep end.

Color is greenish- brown, I thought it was algae at first, did OCLT, no loss. Tried sweeping and scrubbing, and it doesn't come up, doesn't float, doesn't seem to move at all. We've never had any metals problem, so haven't tests in the past 2 years. Stain is around the bottom edge where floor meets wall, around the shallow floor return, and edges on bottom 2 gunite steps.

It won't vacuum, Pool only 2 years old, next step call pool builder?

Water tests yesterday posted below. Calcium has been climbing, we have hard water, even using softened water to add. I've read here no issues with having high CH. According to poolmath spreadsheet, CSI has always been in the green

Chlorine 14
pH 8.2 (added acid to reduce)
CYA 70
TA 70
Cal Hardness 550-600
salt 3400

Hoping the great folks here can point me in the right direction.
Pictures show area near the floor return, and also one of the 'trails' from the middle of the pool
Thanks much

 

[YippeeSkippy]

Get some cheap Vitamin C tablets and stuff them in to a sock, smash 'em up a bit and hold them against the stain for about 5 minutes. See if that changes anything?

Alternatively, grab a single chlorine puck from the pool store (they sell singles) and hold that on the stain (in a different spot than where you did the Vit C test) and see if *that* helps any?

IF the Vit C helped, it implies metal staining. If the chlorine puck helped, it implies organic stains. Let us know how it turns out?

Yip

 

[flipr]

Re: Discoloration in shallow end, won't brush

Get some cheap Vitamin C tablets and stuff them in to a sock, smash 'em up a bit and hold them against the stain for about 5 minutes. See if that changes anything?

Alternatively, grab a single chlorine puck from the pool store (they sell singles) and hold that on the stain (in a different spot than where you did the Vit C test) and see if *that* helps any?

IF the Vit C helped, it implies metal staining. If the chlorine puck helped, it implies organic stains. Let us know how it turns out?

Yip

Well, really no change with either.
Vit C tablets crushed didn't make much impact at all. Couldn't tell at all where it was. Placed sand shark on top of sock to hold in place.

Puck we had was trichloro-s-triazinetrione puck. I think it helped, tried rubbing it on step edge, affect was minute enough it was hard to tell. Let it set for 10 minutes as well, no clear results. Maybe some change, but very slight if there is.

Appreciate the help, any other suggestions?

 

[JohnT]

Rub a spot with a vitamin C tablet directly.

 

[flipr]

Rub a spot with a vitamin C tablet directly.

I was out of town for a couple days, and water was too cold for my wife, but I reached into a step, rubbed directly with 4 tabs in different places, negligible difference at most. Thought while I was rubbing I could see difference, once water stopped rippling, looked much the same as before.

Thanks for checking.