Small Black dots in salt pool. Black algae?

[jeanne3434]

Hi I have tiny black dots in my pool. I went to pinch a penny and they said it was black algae. They recommended taking a chlorine tablet and scrubbing the small specks. They also said that I will never get rid of it and may need to resurface my pool. My pool is only 7 months old. I have gone weekly to this store to get it tested, but missed last week because I was away.

Theses were the stats today before I added 1.7 pounds of stabilizer, 40 pounds of salt and 1 gallon of muriatic acid, and spent the entire day searching for and scrubbing the black dots with a chlorine tablet.

Pool size- 10,884 gallons
Total chlorine- 1.0 ppm
Free chlorine-1.0 ppm
Combined chlorine-0 ppm
PH 8
Acid demand 6
Total alkalinity-125ppm
Calcium hardness-375ppm
Stabilizer-50 ppm
Total dissolved solids-5,000ppm
Salt 3800ppm

I would really like to shock my pool using chlorine bleach and do whatever is necessary to get rid of the black algae that has set up residence in my new pool.

I am desperate to get this under control as economically as possible. I welcome any advice.
Thank you.
Jeanne

[PoolDoc]

Scrap one of the dots with a fingernail or even a toothpick. Smear the black residue on a white card. Black algae smears green.

You don't have to resurface the pool; you will need to run higher levels of chlorine . . . but with stabilizer levels above 50 ppm, you should be doing that anyhow. And . . . you'll need to learn to test your own pool, rather than depending on weekly Pinch-a-Penny testing.

1. Feel free to add plain 8% household bleach -- 1 gallon will raise your pool's chlorine level 5 - 6 ppm. Keep your chlorine levels above 2 ppm ALL the time.

2. Order a K2006 and a K1000 test kit (or get the K2006 and buy a local OTO/phenol red drops kit.) (page with links to Amazon below => K2006 is *not* available locally!

3. Read the Best Guess page, which explains the chlorine / CYA relationship.

4. Keep your pH below 7.8 all the time.

5. Post test results here when you have the K2006. Test strips, even dealer test strips = "guess" strips, especially with respect to CYA (stabilizer) levels.

6. Don't panic. Black algae can be managed successfully.

[jeanne3434]

Thank you.
I noticed that the black dots do not smear at all. They remain intact. Does this mean that they are not algae? Thank you for your help. I will order the test kit.
Jeanne

[PoolDoc]

If you can't scrape anything off, at all, they are not black algae.

Try putting a vitamin C tablet on top of one of them. If it's copper oxide, it may lighten visibly.

Questions:

1. What sort of finish does the pool have?
2. Do you have a heater of any kind? What kind?
3. Have you used any sort of copper, ionic, or 'mineral' treatment or device?
4. Have you used any products -- algaecides, tablets, granules --that contain copper?