Pool Surface Stains/Algae

[DIYconvert]

Thanks to all the great information on this site I'm in the final stages of recovering my green swamp. However, I'm having a tough time with the final stains on the sides and bottom of my pool. There are yellow algae looking stains around the sides and in various places at the deep and shallow ends and darker brown stains on the bottom of the pool and steps from the leaves. At first I tried shocking at the normal shock level of 16 for several days and ran the filter 24 hours/day. Then, after suspecting yellow mustard algae I bumped it up to 30 for about three days but it hasn't seemed to make a dent. I tried to keep it up by checking FC and adding bleach a few times a day (although admittedly I sometimes only checked it once a day.). I also brushed the pool with a 50/50 Stainless Steel/Nylon brush once (sometimes twice) a day. I also did an overnight FC test and it went down less than one. I've gone through countless jugs and spent well over $100 on bleach alone. Is there something I'm doing wrong? Is there a stain product I should consider?

Something to note: I had the pool resurfaced two summers ago (white plaster with a blue dye added) and soon afterwards the blue plaster started to look splotched. It progressively got worse until my pool looked like a tie dyed shirt in some areas and went completely white in some other areas. It seems like the stains are only in the white areas; not the areas where the blue has stayed.

Here are my numbers and some pictures:

FC: Currently maintaining at 7
pH: 7.6
TA: 110
CH: 250
CYA: 38

[attachment=2:nwj319o8]Deep End.jpg[/attachment:nwj319o8]
[attachment=1:nwj319o8]Pool Steps.jpg[/attachment:nwj319o8]
[attachment=0:nwj319o8]Pool Side.jpg[/attachment:nwj319o8]

 

[JasonLion]

Algae brushes off, especially if you brush vigorously. It might come back later, but brushing and high FC levels make it go away at least for a time. If your stains stay around even through brushing they aren't algae.

Leaves, and occasionally algae, can leave organic stains. These stains will fade over time, more quickly at shock level.

Yellow/browns stains can be caused by iron in the water. If you suspect iron, try holding a vitamin C tablet against the stain for 30 seconds and see if it gets lighter or goes away in that specific area. If so, you can either treat it locally with vitamin c, or do an ascorbic acid treatment to the entire pool.

 

[Richard320]

My uneducated eyes see calcium scale that has gotten stained. I believe the scale is softer and more porous than the plaster. What you posted about splotches sorta adds a little credibility to my guess.

Sounds like the shock is done.

I have been having some luck dissolving scale by keeping CSI low. But it is at what I've heard referred to as a Glacial Pace.

 

[frustratedpoolmom]

Do any of the areas feel at all like sandpaper?

 

[DIYconvert]

JasonLion, I tried the Vitamin C test. No change. I think you are probably right about the organic staining from algae. Here's what my pool swamp looked like after I half drained it. (I didn't have enough CYA testing solution so I went to Leslie's and they told me my CYA was 100; turns out they were wrong. Surprise! )

[attachment=0:2c7u4zho]Pool Swamp Half Drained.jpg[/attachment:2c7u4zho]

Richard320, I don't think it's scaling because I've never had high CH. I usually have to add Calcium Up to keep it above 200.

FrustratedPoolMom, the surface always has seemed a little rough to me; however I've always thought that is just what plaster feels like. It doesn't seem any different in the blue vs. white areas. Are you thinking some sort of etching or pitting? I found the following paper on swimming pool plaster deterioration very interesting and am wondering if my pool builder that redid my plaster made a mistake of some sort: http://www.cmc-concrete.com/CMC Seminars/Swimming Pool Presentations.pdf.

 

[frustratedpoolmom]

I was thinking if it was scale you would feel a difference between the two colors.