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So, I'm pretty much done with my drama of this thread:
http://www.poolforum.com/pf2/showthr...hlight=mystery
This morning:
FC = 12ppm
pH -- Not accurate due to high chlorine
TA = 120
CH = 240
But I've still got these persistant dark stains!! They do not brush away, so I don't know if they're algae or metal.
http://imageshack.us/photo/my-images...105071041.jpg/
I don't know what they are. I looked closely at them, and they *look like* some black algae mixed in with some dirt or copper oxide stains.
Here's your pool:
https://lh3.googleusercontent.com/_t...5071041-ed.jpg
And here's some black algae, from I pool I serviced 10 years ago (pics are fuzzy, because it was the first digital camera I had):
https://lh3.googleusercontent.com/_t...CP00376-ed.jpg
Pool view.
https://lh3.googleusercontent.com/_t...CP00381-ed.jpg
You can see, in a closer view, the black algae living in a layer UNDER the surface finish of the plaster.
https://lh4.googleusercontent.com/_t...CP00442-ed.jpg
It's even more visible here.
You can see -- up close -- the green color, but when you step back, it looks black. The test I've always told people for black algae is to scrape some off, and under your fingernail. Then, dry off, and smear the stuff under your fingernail onto a white index card. If the smear is green -- you have 'black' algae.
https://lh6.googleusercontent.com/_t...CP00431-ed.jpg
We removed a lot of it with the pressure washer. Of course, we were also stripping plaster, and exposing the rough undersurface. We finished by rinsing with bleach.
We still had algae problems later, partly because owner would almost nothing herself. She had two teenagers lying around, but they were too lazy to eat a steak if they had to cut it themselves! She ended up ripping me off for over $1,000 . . . because she had a Rolls-Royce appetite, but only a Cadillac budget. She ran out of money before I got my bills turned in.
Ben
The BLACK spots of the picture are actually debris. It's loose on the bottom. The polaris hasn't been used lately because it was just getting too slimy. It's the REDISH BROWN stuff I'm worried about.
Today, on a lark, I tried using my GRILL BRUSH (brass bristles) on them and they WILL brush down. It's orange underneath. I'm going to go out and buy a stiffer bristle brush, and I'm also heating my pool now so I can get into it and scrub harder. I just can't get any leverage on it from the deck..
If you've got access to a scuba divers belt (preferably plastic coated weights*) and you wrap them around your pool pole, and then PULL (not push!) your brush across, you can get good brushing action.
Ben
* Lead weights will leave semi-permanent marks if you rub the pool with them.