Stain identification and removal...

[taekwondodo]

Sorry, no pics (yet) - I'll try to get some later today.

Stains are in the deep end of a plaster pool. They appear to be rust in color, blotchy and varying in consistency and dime-quarter sized. There are several of them. Along the drain it's like whatever formed them mostly settled along the edge of the drain and forms a larger 1/4 semi-circle on the plaster right next to the drain. (Could this be a fertilizer stain...?)

I don't know how long they've been there as my friend just moved in.

Did a D&F as the CYA was well over 200 (now it's 45-50), and before adding Cl I tried scrubbing with first with a Cl puck, then some Vit C tablets to no avail. Had to finally add Cl last night as it's going to be over 100 here for the next several days...

Any ideas are appreciated.

- Jeff

 

[taekwondodo]

Here is a pict:

 

[chem geek]

These look like iron stains. I have some in my pool as well (not as many, but they look somewhat similar) and they were caused years ago when I used Trichlor pucks/tabs in a floating feeder that sometimes parked itself near some stainless steel bars in the pool. The mounts closest by rusted and added iron to the pool and led to staining. In any event, try putting some ascorbic acid (vitamin C tablet) onto the stain to see if it gets reduced. If it does, then it's very likely iron. Follow the procedure in Metals in the Water and Metal Stains to get rid of the stains.

If the ascorbic acid doesn't work, then try putting a Trichlor puck over the stain (or do this first, if you prefer) but not for too long or else you'll leave a mark. If that works, then it's more likely an organic stain and chlorine will remove it, but I'm betting it's more likely to be an iron stain.

Richard

 

[taekwondodo]

I scrubbed them hard with a chlorine puck when I was draining the pool - didn't work. I then threw half-a-bottle of Vit C into a skimmer sock after the pool was refilled and both left the sock on top of the stain for 30 minutes, then went under and scrubbed with the sock - still stained.

 

[chem geek]

I should have read your post more thoroughly since you had said exactly that in the first post. Doh! Well, I don't have any good advice then. Hopefully someone else has some good ideas.

 

[Guest]

Looks like copper stains to me in the metallic form. Sometimes these can be oxidized to the black form and then removed but usually an acid wash is what is needed.
Try putting some dry acid in an old white sock and keeping it on top of a stained ara for about 10-30 minutes (check at 10 minute intervals). If the stain lifts you will need to acid wash.