Treating black algae

[Sarah.dippel]

Hello, we are SLAMing our pool to treat some significant black algae. It’s our third day and we have been running the pump nonstop. Do we need to run it the whole time during the SLAM? Our electricity is quite expensive so I’m a little concerned about that. How long does a SLAM take?
Also should brushing with a regular pool brush during the SLAM be enough? I am brushing twice a day, but so far not seeing a lot of change. I just ordered a new pool brush, maybe that will help?

 

[mknauss]

Welcome to the forum! Please post some pictures. Are you sure it is black algae?
Please read Black Algae. You do NOT follow the conventional SLAM Process for black algae.
Brushing black algae is required. Some have found alternative ways using wooden skewers, low rate pressure washers, etc to disturb the black algae.
A long period of elevated FC is needed. But NOT SLAM level. And no real need to run pump all the time as you are not filtering dead algae from the pool.
I suggest you read through Pool Care Basics - Trouble Free Pool and even look at a few of our videos TFP-TV - Trouble Free Pool

 

[Sarah.dippel]

I believe it is black algae, what do you think? Our FC is at 15.5 right now. My CYA is 50 so the TFP calculator said that I need to be at 6-8 consistently. So stay at 8-SLAM levels per the article? Also can you recommend a stainless steel brush? We have been really worried about harming the plaster of our pool by using one.

 

[mknauss]

Can you scrape off some the area and see if it smears green?
I am tagging @JamesW. This looks like some or all staining.

 

[JamesW]

Is the pool painted?

Are you new to the property?

Can you show the system?

If you rub your hand on the wall, does it leave white residue on your hands?

 

[Sarah.dippel]

Can you scrape off some the area and see if it smears green?
I am tagging @JamesW. This looks like some or all staining.

Upon closer inspection most of the coloring is gray, and I can’t feel anything when I put my finger over it. There are some black spots and those do scrape off and smear green.

 

[Sarah.dippel]

Is the pool painted?

Are you new to the property?

Can you show the system?

If you rub your hand on the wall, does it leave white residue on your hands?

We have lived here almost 3 years, but we have not done the best job maintaining it. We are using TFP and learning a lot. No residue when I rubbed my hand on the wall. Is there an easy way to know if the pool is painted? Also can you explain what you mean by show the system?

 

[mknauss]

Upon closer inspection most of the coloring is gray, and I can’t feel anything when I put my finger over it. There are some black spots and those do scrape off and smear green.

I wonder if the plaster is gone in those areas? It looks to me that it is time to start considering a replaster job.

 

[JamesW]

It looks like pitting in paint or plaster.

Black algae tends to grow in pits, so it might be black algae.

Paint will generally rub off on your hands.

The system is the equipment like the pump and filter.

 

[Sarah.dippel]

I wonder if the plaster is gone in those areas? It looks to me that it is time to start considering a replaster job.

My husband says it is not painted. Is the plaster a cosmetic issue? If it’s just ugly but clean of course that’s not preferred but we can tolerate that.

 

[JamesW]

Is the plaster a cosmetic issue?

Mostly, but it makes maintenance more difficult.

You need to brush often and well and you need to be extra diligent about maintaining the chemistry.

 

[JamesW]

My husband says it is not painted.

Are you 100% sure that it is not painted?

If yes, how are you sure?

It might not be paint, but it looks like paint to me.

 

[Sarah.dippel]

If I’m not getting a white residue on my hand is there another way to know? He doesn’t think it’s painted but we don’t know how to be sure. Here is a picture of the system

 

[JamesW]

You can try to scrape off a thin layer with a knife or sharp wood chisel to see if it is paint or plaster.

If you get a chip that looks like paint, it probably is paint and you can put it in paint thinner to see if it dissolves.

 

[JamesW]

I would guess that the pool is over 40 years old, so there's no telling what has been done to it over the years.

Paint is often used as a cheap coverup when selling a house because it looks good for a little while before falling apart.

When you brush the pool, do you get a white cloud?

 

[Sarah.dippel]

Yes there is a little bit of a cloud but I wouldn’t call it white more like a little gray. And it’s not a big cloud. For context our house was built in 92. Not sure whether it was original to the house or put in later. The system that I sent you a picture of is one that we bought used. Our pump and filter blew up in the ice storm and became very hard to come by, we were very lucky to find replacements even used ones.

 

[JamesW]

See if you can scrape a spot to verify if you have paint or not.

The filter threw me off on the age.

You can check the permits for your property to see when the pool was installed.

 

[Sarah.dippel]

I will check that. Unfortunately, we do not have the money to replaster the pool so we will have to do our best with what it is.

 

[JamesW]

Ok, understood.

You probably need to SLAM and brush to see if it can be improved.

Knowing if you have paint or not would be very helpful.

 

[Sarah.dippel]

Ok I took a knife to a spot on the wall. It did not come off like a paint chip, it came off as a dust. And I just got a new nylon brush, I am getting the white cloud that you were asking me about