Algae after ascorbic acid treatment

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swimming3

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May 26, 2020
15
Austin
Hi all! I did an ascorbic acid treatment on my pool about a month and a half ago - did wonders! However, I've now been battling algae since then and can't seem to beat it. I believe it is black algae as there are dark specs on the pool wall. Also, we seem to get areas of what looks like red spots along the side of the pool. I've attached photos of both. You can't really tell the larger spots are reddish in the photo. I'll try to take another picture when the sun is behind a cloud. Can anyone advise if 1. this is indeed black algae and 2. how to beat it!! I've been shocking and scrubbing to no avail. I've also considered that it could be metal redepositing but I don't think so - it was a yellowish color.
IMG_4579.JPGInkedIMG_4584_LI.jpg
 
So, you appear to have two concerns - algae and staining from metals (iron or copper).
ALGAE: The fix is always a proper SLAM Process using one of the recommended test kit. See Test Kits Compared. Do you have a TF-100 or Taylor K-2006C? If so, please add it and all of your pool and equipment info to your signature. That will be useful as we go forward. You can try to scrape some of it onto a a paper towel.

METALS: First it's best to know which metals do you have and how did it get int e water? Iron (tested with Vitamin C tablets) is usually from a well, but some municipalities have an elevated iron level as well. Copper (sometimes reacts to dry acid in a thin sock) is from copper-based algaecides or perhaps a bad heater element. Do you know which metal you have in the water?

In either case, if you have algae, you must properly complete the SLAM Process before going back to readdress iron/copper staining.

www.troublefreepool.com

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 www.troublefreepool.com
 
Yes, we definitely had iron staining. Basically the entire pool was yellowed over 7 years or so. I ended up having to use 5 lbs of ascorbic acid.

We assume the city (Houston) water must have a high iron content because that is the only source of water for our pool other than rain. Our pool turned blue again overnight. It was great until..... algae. I've been adding sequestrant weekly (Proteam Metal Magic).

The larger "stains" aren't stains. They brush off. I believe maybe another type of algae... not sure? The small black spots do not. I believe that is black algae so I plan to do another week of shocking and brushing. We were out of town the last week. My dad kept the chlorine levels up but it appears he stopped monitoring the pH because it was off the charts this morning. Regardless, these issues started several weeks ago.
 
Okay, so then it appears algae is definitely job #1. Just make sure to follow the SLAM Process carefully and thoroughly. The BA will require additional,aggressive treatment as you go through the SLAM Process. During the SLAM, some of your iron staining may return due to the elevated FC level. You'll just have to let it happen and treat afterwards. During the SLAM Process, get some polyfill in the skimmer and try to catch as much iron as you can.

Now once you are satisfied with the BA treatment and complete the SLAM Process, there are some things to think about for future iron treatment:
- If you do another AA treatment, make sure to use some polyquat 60 algaecide to help prevent algae while the FC is close to zero.
- In the future, keep the pH no higher than 7.5 if you can.
- Post AA, keep the FC and CYA balanced well as noted on the FC/CYA Levels
- Continue to use a good sequestrant

You might also take a look at your local city annual water report online to see what they show for an iron level. If there is none (or very low), maybe you have some older steel pipes underground. Something to consider I suppose.
 
Did you keep your FC up after the AA, 5 pds will neutralize a lot of Chlorine and it's a battle to get it back up. I had stains that seem to be in the plaster and had to use 10 pds but bought a lot of liquid Chlorine and Calpo Shock before hand. I did mine 2 weeks ago and just now have it where the SWG can maintain it with out adding

But either way do what Pat suggested and SLAM it and kill it :)
 
I hadn't heard about polyfill. Thanks - will check it out. Do you have any experience with CuLator?

I did have polyquat 60 in the pool during the AA treatment. Not sure what introduced the black stuff. I haven't had any issues with metal re-staining through the various shock treatments so I guess the sequestrant is doing its job.


My CYA is around 30 and my FC is just over 4 ppm currently.
 
markayash said:
Did you keep your FC up after the AA, 5 pds will neutralize a lot of Chlorine and it's a battle to get it back up. I had stains that seem to be in the plaster and had to use 10 pds but bought a lot of liquid Chlorine and Calpo Shock before hand. I did mine 2 weeks ago and just now have it where the SWG can maintain it with out adding

But either way do what Pat suggested and SLAM it and kill it :)
Click to expand...
markayash said:
Did you keep your FC up after the AA, 5 pds will neutralize a lot of Chlorine and it's a battle to get it back up. I had stains that seem to be in the plaster and had to use 10 pds but bought a lot of liquid Chlorine and Calpo Shock before hand. I did mine 2 weeks ago and just now have it where the SWG can maintain it with out adding

But either way do what Pat suggested and SLAM it and kill it :)
Click to expand...

I did! Religiously, multiple times per day!! Sounds like I'm going back to shock heck. Gah!!!!
 
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