Thought it was poop.... black algae??

[Modawg2k]

I've had black specs in my pebble that have been increasing over the past few weeks/months. I have a 3 year history of not maintaining my water chemistry very well up until a couple months ago when I found this site. With the exception of CH (which I plan on doing a drain in the next week), I've kept a good eye on my numbers lately. In the past week, my chlorine got knocked down to zero because my SWG breaker got tripped and I didn't test for a few days. I'm currently shocking it. Earlier this week, I went into the pool and took a pool wire brush to some of the black spots (which have a smooth, slimy feel to them) and they will scape off and disintegrate with some hard rubbing. Do you guys feel that black algae is the culprit here?

My current reading:
TC: 15.5 (more chlorine was added after reading to obtain shock level per pool calculator)
pH: 7.8 (MA added to obtain 7.4 per pool calculator)
TA: 80
CYA: 80
CH: 850

 

[linen]

It sounds like black algae...are they green on the inside?

 

[JasonLion]

Given that they don't come off with casual brushing, then if you can scrape off a bit of one of the black dots and smudge it across a piece of white paper, and it smudges green, then it is black algae.

 

[Modawg2k]

I will check into that once my FC gets down from shocking , thanks guys

 

[techguy]

I would check before your shock is done and possibly even raise your FC since its already up. If the top scrapes offs and makes green smudges, scrub the tops off to let your nice high FC get into the base layer.

You are safe to swim all the way up to the shock level in the PoolSchool chart which is much more aggressive than PoolCalculator.com. Above that you risk fading your suit but that may be a fair cost to rid your pool of the algae.

 

[Modawg2k]

Thanks. Any issues with being in the water to brush algae? Seems harder to get a good scrub with a pole

 

[RobbieH]

Are you using a regular brush or a wire brush on the pole? It takes some elbow grease for sure!

 

[Melt In The Sun]

I'd get a little tiny wire brush (toothbrush size, like for cleaning paintbrushes) and scrape it underwater with goggles. In my experience, the big brushes don't work as well since you can't push as hard on a little spot.

 

[RobbieH]

One of my hobbies involves welding, and I have found these welding brushes to be really good for this.

You can get them just about anywhere that handles hardware, tools, etc.

 

[techguy]

I second the idea of a smaller stainless brush, maybe even a brass brush to localize the scrubbing on the spot.

That being said, I have vinyl so I may be incorrect.

 

[Modawg2k]

Are you using a regular brush or a wire brush on the pole? It takes some elbow grease for sure!

I'm using a smaller wire brush that attaches to the pole. I like hand scrubbing for sure.

 

[Modawg2k]

I'm draining the pool right now due to a high CH factor and I scraped one of the black spots and it's definitely green on the inside. Thinking about doing a chlorine wash over the areas