Newby w/ black algae spots

[jwesleyh]

New house with pool. I've been following the TFP program religiously for about a month now. Noticed when I bought the house mid-Nov a few black algae spots on a horizontal seat. Thought maybe with cold water and time they'd go away considering higher chlorine levels I'm running because of elevated CYA, which I'm hoping winter rains will help bring down. Not spreading but also not fading or brushing away easily. Water otherwise looks great.

Any advice? Leave and let chlorine slowly kill over winter or worth SLAMing now? Any advice on stiffest brush to scrub them that won't harm colored plaster?

Most recent poolmath #s as follows:
FC 10, PH 7.6, Alk 100, CH 400, CYA 80, Water Temp 58 (Texas).

Very grateful for the wealth of info offered by TFP. Saved me from the pool store trap! Thanks in advance!

 

[ajw22]

Black Algae

This guide provides a step by step procedure for eliminating black algae in your concrete or gunite pool. Read full post here.

www.troublefreepool.com

Gently scrape a sample of the suspected black algae with your fingernail and then smudge it on plain white paper. If the smudge scrapes off and is a greenish color, then it’s black algae.

For Black Algae, you will have to physically disrupt the surface of the algae. You can use a wire brush or if it is just a few spots, put on a mask and snorkel, go into the pool, and pick at it with a bamboo BBQ skewer.

If you have more than just a few spots, get in the pool with a weak pressure washer, and you can use that to blast away the BA.

After you have physically disrupted the BA, you should dose it with Liquid Chlorine. Get the strongest LC you can find, and if the BA is close to the edges, pour the chlorine down the side where it washes over where the BA used to be. If the BA is all over the place, you can fill a 1-gallon pump sprayer, get into the pool, and spray those spots. And yes, you can do this all underwater.

Then you need to keep your FC at 20% of CYA for the next several weeks.

 

[jwesleyh]

Thank you. It's black algae, scapes green. Will treat it as indicated.

 

[jwesleyh]

Just wanted to report back and say thank you again. Treating as you suggested knocked if right out.