algae help. can't seem to make progress

[Sulewski]

I have been traveling a bit this summer and have not been very good about my pool monitoring. I log most of my testing into pool math and my finish is EcoFinish. I administer liquid chlorine daily into my pool using a Stenner pump and a timer. Thanks to this site I have not a problem with my pool chemistry for quite some time. I took that a little for granted and slacked on the daily adds to the pool. My pool has two things going on please see the pictures to see the small black spots along the shady side of my pool. I think this may be black algae. I've had a hard time getting my free chlorine up to SLAM levels and bought some Dichlor at the local shop. Now my FC is sky-high. I continue to brush the algae twice daily and I am hoping this takes care of it. My deep end is 10 ft deep and it is not easy to get in and scrub the spots. I am using a brush on a pole.

The second issue I want to deal with is a few rust spots that have been caused by two bolts and a drill bit left behind by a contractor replacing a fence. I purchased some vitamin C from Costco today and will attempt to crush some tablets and put them in a skimmer sock and see if these help the rust to fade. Is there anything more that I need to know before I do this?

Any input or advice is appreciated. So grateful for this site and the availability of the pool test kit. You make it so much easier to have a pool!

 

[PoolStored]

You are on the right track.

Follow the SLAM process. Print it out, read it three times, keep it in your back pocket. Link-->SLAM Process

When you are done, follow the instructions here if the black spots persist.

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

Rubbing the vitamin C should clear your rust stains...

 

[Sulewski]

I just cleaned out my robot and found this. I am now thinking we have rust all over the pool. Little spots of it like you can see in the picture. I cleaned one portion of the cleaner with crushed vitamin C so I assume that it is iron. Help! I thought I was fighting black algae. My chlorine is in the 20s.

 

[proavia]

Focus on the SLAM Process

Worry about possible rust and staining after the SLAM is completed.

 

[PoolStored]

^^^^Agree with @proavia.

On a separate note, do you fertilize or have a fertilizer company that has come in the last short period of time?

 

[bradgray]

Maybe it's my phone or tired eyes, but I'm not seeing algae.

I've seen organic stains in fiberglass pools similar to this, but yours appear more like metal staining. Ecofinish is virtually impregnable to black algae and green algae doesn't "spot" as often as it "coats".

You said you had a fence redone - was it metal? I'm highly suspicious of swarf from welding or drilling.

 

[Sulewski]

Maybe it's my phone or tired eyes, but I'm not seeing algae.

I've seen organic stains in fiberglass pools similar to this, but yours appear more like metal staining. Ecofinish is virtually impregnable to black algae and green algae doesn't "spot" as often as it "coats".

You said you had a fence redone - was it metal? I'm highly suspicious of swarf from welding or drilling.

Thank you for your reply. The fence was completed in the winter before the pool season and the spots were not there in the beginning of the summer. There was no machining just assembly of the cable fencing so I don’t think there was small debris that would have made the small spots. The eco finish has been down three seasons and I’ve not had a problem like this. I agree it’s pretty impossible for things to penetrate. That said I had the water checked for metals and there was no iron and a trace amount of copper. I continue the slam process losing 3 ppm overnight. So I will continue to slam until I at least don’t lose chlorine overnight. If the spots are still there I’ll look into a process to address staining as if it were from iron. I’ve been using a metal brush on the spots twice a day. I do think they are getting smaller. But it might be wishful thinking.

Do I have to worry about a metal brush on the eco finish. Will I damage it?

 

[bradgray]

Do I have to worry about a metal brush on the eco finish. Will I damage it?

Short answer is yes. It can technically scratch the material.

In the real world, it's hard to notice. I wouldn't lose sleep over an occasional, justified stab with a metal brush. But I would not recommend regular brushing with the metal bristles.

 

[Mdragger88]

Be aware that the dichlor raised your cya by 5.5ppm - anywhere between 50 & 60 counts as 60.
Slam level is 24ppm
FC/CYA Levels

 

[Sulewski]

I have been working at this for a long time and have seen just a little progress. I did purchase a brush made for Gunite pools. It's the green and grey one that is made by Animal. It has some tooth to it but is not metal so I don't think it will damage the ecofinish. One of the guys that worked for our pool builder has since left that company and does some maintenance on his own. I talked to him about the marks in the pool and he immediately said it's black algae. He has two other pools in the area that are dealing with it and have never had a history of it. He is adamant that I get the phosphates removed from the pool. I did take pool water to two different pool supply places. One didn't register any phosphates and the other measured about 700. I am torn about whether I should purchase a phosphate remover because of all that I have read on this site. I told the pool store guy that I had read on a pool care site that phosphate removal should not be necessary as long as I am brushing and maintaining a high level of FC. He said well you can believe me or the internet. I won't be purchasing anything from that pool store anymore.

Additional info: I have a sand filter. The black algae is in the deep end of the pool. Thoughts on an easy way to rub the pucks over the algae in a deep end? Should I purchase a K-1106 kit for phosphate testing?

thank you for your help in this!

 

[JJ_Tex]

24 days is a frustrating time for a SLAM. Lets take a step back and re-look at some of the basics:

1. How confident are you in your CYA number? If that is off it could also mean that your SLAM target is off as well which can prolongue a SLAM.
2. Have you checked for hidden algae in stairs, behind lights, skimmers, etc?
3. How does your water look? In your first picture you water is pretty clear and I would not have expected a SLAM to take a month with that level of clarity. Have you done an OCLT recently and what were the results?

 

[Mdragger88]

Slam should clear up regular algae & generally lessens black algae but will not banish it.
Putting chlorine directly on the black algae & frequently scrubbing it is how you get it under control.
If you have passed the oclt & all other algae is gone (crystal clear besides the stuff that won’t scrub off) you can maintain fc somewhere between high target & slam while you work on the black stuff.
Some have had luck with using liquid chlorine in a pump sprayer to get to the hard to reach areas along with aggressive brushing.

 

[Sulewski]

When I first began the SLAM the chlorine dropped by quite a bit overnight. Now it's 1. I have read the advice about maintain fc between high target and slam. That helps. Any thoughts on the phosphate?

 

[Mdragger88]

I wouldn’t worry about the phosphates. If the level was crazy high or something- maybe. But not until all algae was gone anyway.

Phosphate Removers - Further Reading

www.google.com