Dang black spots, be gone!

[jamescl]

Hi all, bought a foreclosed house a couple months ago, pool was pretty nasty, so it took quite a bit to get it usable. The service I worked with had me add 25lbs of baking soda, lots of chlorine, new filters, and 2 weeks of constant filtering. Wish I had the original tests but I've lost them (arg).

Water looks great now and we've used it quite a bit, but for the life of me, I can't get these black spots out of the plaster and more seem to appear each week. The pool and spa also have splotches which I assume is plaster wear?? For the black spots, I've been mainly scrubbing (hard as heck) with a wire pool brush. I tried a crappy pool stone, but that did nothing but disappear in 30 sec.

Recent test results (from pool service, using manual test with taylor kit):

• TDS: 410
  CYA: 50
  Tot Chlorine: 8
  Free Chlorine: 8
  PH: 7.6
  TA: 140
  Total Hardness (?): 150

This is my first pool so everything is new to me. Appreciate any tips you can spare, thanks!

[attachment=1:yi6qec1j]pool.JPG[/attachment:yi6qec1j]
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[attachment=0:yi6qec1j]bottom.JPG[/attachment:yi6qec1j]

 

[BoDarville]

Re: **** black spots, be gone!

Welcome to TFP

Before you try too hard to remove those black spots, it's possible that they may have been added to the plaster intentionally as a non-slip surface to allow your feet a better grip, especially when entering or exiting the pool/spa. We have that in our current spa and when we first moved in (as a first-time pool owner) I thought it might be black algae. Pool service save me from myself at that time.

BTW, your numbers look fine. You can ignore TDS - completely irrelevant to managing a pool.

 

[duraleigh]

Re: **** black spots, be gone!

Black algae will scrape off (partially) with your fingernail and then, if you smear it on a white piece of paper, will appear as a dark, blackish green streak

 

[jamescl]

Re: **** black spots, be gone!

The spots are random throughout the pool, just more heavy near the step so I'm pretty sure it's not part of the design, but appreciate that warning.

It's not coming off with heavy brushing, I also tried just smearing some paper towel on it, but nothing transferring to it so I don't think it's black algae either.

I'm going try dropping some granular chlorine on it to see if that does anything. It's white plaster so I figure bleaching it can't hurt ; )

 

[Butterfly]

Re: **** black spots, be gone!

Black algae will scrape off (partially) with your fingernail and then, if you smear it on a white piece of paper, will appear as a dark, blackish green streak

It's not coming off with heavy brushing, I also tried just smearing some paper towel on it, but nothing transferring to it so I don't think it's black algae either.

We usually recommend paper like a business card stock. Not paper towel.

Black algae does not 'come off' with heavy brushing. Black algae is a hard algae, hard as in must-knock-off-tops-w/stainless-steel-algae-brush hard, and then treat aggressively w/chlorine. There is more to learn about how to treat BA. You can use google, bottom left of each page.