Help me identify this!

[tk707]

New and mostly clueless pool owner so please bare with me.

Things have been going great with my pool, water has been crystal clear, all my levels appear to be appropriate etc. BUT....

I have noticed over the past few weeks the development of these dark circular brownish/green spots. I didn't pay much attention at first but now they seem to be multiplying. I tried scrubbing them out, no luck. I tried scrubbing them viciously with vitamin C tablets, no luck. It should be noted, these are developing at the bottom of my "deep" end almost directly underneath my pool light which I observed to have just a little bit of rust as well as some metal shavings on it. Can somebody help me identify this, I know these photos aren't great I tried to get a decent shot of them. Its not the type of issue that's going to cause me to stop swimming and my wife tells me I'm overreacting and it isn't a big deal but my mindset is I am trying to prevent this from becoming a real problem.

I appreciate any help and advice, thank you very much!

 

[Flying Tivo]

I think you could have debrie inside the pool light nitch. Dive in and open it up and do a little cleaning. Try Ascorbic acid for those stain and tell us if they dissapear.

 

[Richard320]

I can't see them clear enough.

Do they look like the pool has moles? (Skin, not animal.) That could be black algae. If you can scrape it off with a fingernail and then smear it on a piece of white paper, is it real dark green?

And this is a big ? to us
"all my levels appear to be appropriate etc."

Test results are what interest us; objective numbers, not opinions.
We can form our own opinions.

 

[tk707]

I can't scrape these off for the life of me, vitamic C hasn't worked and I took a brush down there as well with some elbow grease and they didn't budge.