Yellow stains in deep end of pool. Any advice?

[ravinath]

Hi, new pool owner of an old saltwater concrete pool. Looking for some advice on how to treat the yellow stains on the floor in the deep end by the main drain. Water chemistry looks pretty good overall based on my testing. Thanks in advance for your help!

Attached my pool math results here too. Ph has been in the 7.6 - 7.8 range for the last few weeks until yesterdays reading.

 

[Texas Splash]

A little hard to tell from the pic if it's iron or organic. Try rubbing a Vitamin C tablet on the stain (iron), and if that doesn't work, try rubbing the area with a chlorine tablet (organic). Let us know if any of those work.

 

[ravinath]

Thanks. One question: vitamin c? Meaning over the counter vitamin c pill?

 

[Texas Splash]

Meaning over the counter vitamin c pill?

Yep. Same stuff. The tablets, not capsules or gummies.

 

[Mdragger88]

Crush em, put em in a sock & hold it on the stain with a brush/pole - come back later…

 

[ravinath]

Alright, the chlorine puck didn't remove the stain and I've used this before on other leaf stains and worked very quickly. It's been almost 5 hours with no change to the stain. I will try the vitamin C next.

 

[ravinath]

Hi All, i did the Vitamin C test as well and the color changed from mustard yellow/brown to grey but the stain didn't really go away. Any recommendations.

 

[mknauss]

Do you use copper based algaecide? Or any type of ionizer?

 

[ravinath]

No I haven't. We had this problem last year as well but this year, it seems to have spread a bit more wider. Do you recommend trying a specific algaecide in that area?

 

[mknauss]

No. I suspect a metal stain, but not iron.

The change in color when Vitamin C was applied can imply copper, or silver.