Black Algae persistant

[Oclat]

I'm 100% sure Ive got the dreaded black algae in my pool. I've succumbed to live with it as I have had it about 4 or 5 years now. I'm looking forward to winter as the pool will not have blooms with the water temps dropping.I have it at least 4 or 5 times a year throughout the warm season. I am in North Carolina. The pool is a gunite inground 20 by 40 with Diamondbrite exposed aggregate plaster which also has some black aggregate throughout. I believe it is the "ivory".( although it is bascially a white plaster with aggregate mixed in)There are so many nooks and crannies with this type of plaster that brushing is an exercise in futility. It hides everywhere, ladder steps, behind steps, behind pool lights, etc.... it is a pool cancer IMHO. So basically, I just get in the pool when it blooms and with my pressure washer spend a couple of hours blasting the spots. The pool was built in 2001. I basically use BBB and occasionally trichlor tabs when I'm out of town. I also use Calcium Hypo to keep calcium levels up. I really think that this algae is inherent in the plaster, water etc. I just had a recent bloom as temps here when in the 70's for a period of time. If I ever re-plaster this pool, the plaster will be smooth, not like this Diamondbite product. So, I guess my question is, can I get rid of it? Even when I pressure wash each and every spot I see, there is no way to get every one, (virtually impossible). It is so frustrating, discouraging, etc.etc. If I super chlorinate during when it is dormant, will it do any good? Or should I just wait till the next bloom next spring/summer and pressure wash ( although, I will not get every spot, etc., then keep at 30ppm chlorine for 2 weeks and give the ole college try once again, even though every place is not blasted, ie behind pool lights, under steps on pool ladder.

I long for the the simple stuff, like a little green algae on the walls of the pool. That is so easy to cure.

Frustrated in NC,

Steve

[Phillbo]

Drain it , spray it with pure bleach and let it dry out?

[CarlD]

I'm no expert on hard surface pools but the power washing may actually be abrading the surface allowing MORE nooks and crannies for the algae to bed in.

But what I didn't see in your post was your raising your FC level extremely high and keeping it high (Like, say 50 or 60ppm) to attack the algae. You should also consider raising your borate level to 50ppm (use Borax to raise borates, and muriatic acid to adjust pH down) as it inhibits algae.

Meanwhile, please provide us with detailed test results as well as the gallonage of your pool.