Is this Algae?

[JimmyMan123]

My pool needs to be resurfaced for sure, but I wish I could ge this black stuff off the bottom

It was there from when my pool was 100% green and filled. Since then I got a new filter and pump and in a very short time I got the water 100% clear. The problem is that there is this big-ol black spot on the bottom

I have a Algae brush which I try to go over it, but it almost seems like I am not making a dent in it at all whenever I try it. Any ideas or tips?

 

[mknauss]

Any copper based algaecides used? Do you have a heater?

 

[JimmyMan123]

None currently but they may have in the past, no heater

I think when I first moved in I dumped a bunch of shock in, which did have copper

 

[mknauss]

They look like copper stains, or another metal.

To check on if they are organic, take a puck and set on an area for a few minutes (no longer). See what happens.

 

[JamesW]

The turquoise looks like copper. The black might be copper or maybe black algae.

If it's black algae, you should be able to scrape some off.

Black algae is similar to black mold. It's soft, but it grows roots into the plaster.

If you can scrape some off, it should be blue-green and mushy.

If you can't scrape anything off, it's probably copper.

You can use sulfamic acid (Jack's #2 copper and scale stuff) to treat it.

It might not come off.

Even if it does come off, the copper is in the water and you would need to drain and refill to get rid of the copper.

Don't drain without consulting a local professional expert because the pool can float if the water table is high.

You can try to manage the copper without draining, but it's a significant challenge to keep it from restaining.

Also, sulfamic acid converts the fc to cc for months.

 

[JimmyMan123]

Good information guys, ill try the puc trick and see what happens

If it is copper, I might just leave it for when they resurface the pool. That would require a drain anyway

 

[JamesW]

Try vitamin C on a spot.

 

[JimmyMan123]

What would Vitamin C do?

If I try the puc, would there be a clear spot under it if it was Algae?

 

[mknauss]

Vitamin C is ascorbic acid. It will clear iron immediately and may change the color of the stain if another metal.

If organic the puck will clear it or at least dramatically lighten the stain.

Read Stains in Your Pool - Trouble Free Pool

 

[JamesW]

Vitamin C might make a clear spot or a darker spot. We're just looking for some sort of reaction.

 

[JimmyMan123]

Thanks guys, ill go out now and try the puc, don't have any Vitamin C at this current moment

 

[JimmyMan123]

Chlorine puc did lighten it a lot, also made it easier to remove the stain

In this case, is it just a case of really working at the stain with a hard brush?

 

[mknauss]

Interesting. Can you get and post a decent picture of the results?

 

[JimmyMan123]

Ill go out in a moment and take some

If I brush at it hard with an Algae brush, I do get some green cloud/particles coming off. Its not totally clean under the puc, but there 100% is a difference

 

[JamesW]

It could be black algae. Black algae grows roots into the plaster. So, it's very difficult to remove.

 

[JimmyMan123]

The plaster is already chipping off, so I imagine it was even easier for it to get in there and grow

 

[mknauss]

Read Black Algae - Trouble Free Pool

Sounds like you are due for a chipout and replaster. Might want to just live with it until that is done.

 

[JimmyMan123]

Yeah, I'm going to try my best to get it clean, but I'm not going to go too crazy

This time last year it was 100% dark green, so we are going in the right direction...

 

[JamesW]

Black algae is toxic. So, I would try to get rid of it.

 

[JimmyMan123]

Maybe Ill make it more of a priority then, but I'm not too concerned

Would a good plan be to just ramp up the chlorine level and have a good scrub every day?