Mystery stain in catch basin

davidhum66

Bronze Supporter
Jul 8, 2018
24
Austin, TX
Greetings - wondered if anyone might provide clue as to the brown staining in the pictures. I have a catch basin that has plaster and my pool has a pebble tec finish. Don't know why pool builder did it this way. Pool was built in '02 and last summer, I painted the catch basin to address some minor stains and give it a fresher look. However, in Oct, noticed brown, rust colored stains in this corner. I am pretty sure there was similar stain prior to me painting last summer. No where else do I see this staining. Pool chemistry is closely watched (thanks to TFP guidance vs LPS in the past). I tried using stain remover, rust remover, and nothing worked addressing/removing stain. I am wondering if there is rebar right behind the lower tile and this is rusting and bleeding out the color into the plaster and catch basin wall. The basin is lowered a few inches as I was planning to work on it again. Basin is constantly having pool water come over pool edge, so this corner is constantly "wet" with running water, so its possible that metal in the water is collecting there and staining (?). But again, no other place in pool or spa have these stains. I may just leave as is given basin is not viewable from patio. But if I did want to address, any suggestions on what this might be and how to address? Chip away tile to see if there is a crack in that corner leading to the metal rebar? And if that is the problem, how do you patch. Assume some kind of water proofing material like that used in shower walls? Or am I off base with what this might be. A project maybe I'll tackle this summer. Thx for any advice.
 

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ajw22

Gold Supporter
TFP Guide
Jul 21, 2013
20,445
Northern NJ
My vote is rusting rebar behind that area. You have water leaking into the area from the pool or deck and rebar rusting and flowing out.

@bdavis466 how would you tackle this?
 

davidhum66

Bronze Supporter
Jul 8, 2018
24
Austin, TX
Thanks for the feedback. I’ll tackle this spring. Plan to remove those tiles pieces and chip away and see how far in I can go before seeing metal/rebar. Plan to follow the staining. I can fully drain the catch basin easily, so will be easier to get into that corner area.