So I used some copper algaecide to try to treat black algae. Didn't work. Now what?

JCD3nton

Member
Jul 6, 2020
15
laredo
Yes, I know everyone here opposes copper algaecides, but I had to try it as a method of last resort to treat my black algae.

I've read just about every article on the internet and tried the "proper" methods. I think the algae was embedded in my pool too long for normal methods to work though. The heads are so hard that scraping them with a wire brush literally does nothing to them. The only way I could actually get the heads off was using a paint scraper on a pole, with a snorkel and a swim mask so I could see exactly what I was doing. Did my whole pool like that, and algae certainly isn't spreading or growing, but even high levels of chlorine made minimal further progress to get rid of the residual stuff still left on the walls.

Phase 2, I saw a few people on this forum say they had success using a pressure washer underwater. Bought a 3300 PSI pressure washer and turbo nozzle. To a certain extent, it does knock the residual algae off, but only when using a turbo nozzle, and only at point blank range. Unfortunately it also occasionally knocks off a chip of plaster. With this I can actually make some continued progress after scraping, but it's a very slow process, dot by dot, with some risk to the pool surface. House was built in 2007 so I feel like there's probably a resurfacing in my future anyways, meaning some collateral damage is acceptable.

Finally, since nothing else was successful in fully getting rid of the black algae, I decided to try the InTheSwim black algaecide, which has copper in it. I hoped based on reviews that it might weaken the algae enough for it to come off easier. Well unfortunately I wasn't one of the lucky ones, it appears to have done almost nothing for me. So now I need to figure out how to get this copper out of my pool. My understanding is that if I dump chlorine in there, it may oxidize the stuff and turn my water green. Actually it seems like right now, the algaecide has eaten all of my free chlorine. My understanding is that you are not supposed to shock and add algaecide at the same time. However, none of the articles talk about what to do after.

Is it going to be impossible to maintain free chlorine in the pool until after all the copper/algaecide is gone? Or can they coeexist? What is the best product to get the copper level down?
 

JJ_Tex

Bronze Supporter
Jul 17, 2019
1,532
Prosper, TX (DFW)
You seem intent on manually removing the black algae, but never mentioned your chlorine levels. At they at or near SLAM levels? It is the elevated chlorine that is going to kill the algae.
 

JCD3nton

Member
Jul 6, 2020
15
laredo
You seem intent on manually removing the black algae, but never mentioned your chlorine levels. At they at or near SLAM levels? It is the elevated chlorine that is going to kill the algae.
Yeah, I tried the recommended method here, didn't work past a certain point. From everything I've read, manually removing the black algae is what is required . . . it has to be manually removed in addition to high chlorine.

My chlorine levels were previously high while I was doing these things. After adding the algaecide (I let chlorine drop to 5ppm before I added it), my chlorine is gone. Now I'm trying to figure out if I should be shocking the pool with this copper now in it or if that is just going to turn the water green and lead to more problems.
 

JCD3nton

Member
Jul 6, 2020
15
laredo
Were you brushing daily with a steel brush?

Yeah. I read the articles. They didn't work. After a lot of brushing from outside the pool using a pole/metal brush with nothing really happening, I decided to hop in with a mask and snorkel to see what was really going on. Even brushes with bristles much stiffer than a normal pool brush wouldn't take it off scrubbing directly. Only a paint scraper actually took off the algae heads.

But this isn't about how to treat the algae. It's about what to do with chemistry. My pool water is sparkling, crystal clear right now (other than patches of black algae on the sides of the pool). However, it's not holding chlorine. I put in 10ppm last night and it's at 0 free chlorine right now. Is it the algaecide doing this? The instructions say chlorine is needed along with the algaecide to control bacteria, but it seems like chlorine/copper cannot coexist in my pool.
 

YippeeSkippy

Mod Squad
LifeTime Supporter
Jan 17, 2012
14,431
Evans, Georgia
There are other, more expensive and copper free algaecides. But once algae is in there its useless to add the preventative algaecide.

10ppm of FC is probably not even touching that stuff if your CYA is higher than 40ppm. What *is* your CYA?? What are all your current test results??

FC
CC
pH
TA
CH
CYA
Salt if applicable.

Maddie :flower:
 

JCD3nton

Member
Jul 6, 2020
15
laredo
I just realized that the chlorine (cal hypo granules) may not be dissolving normally. It was on the floor, and after being stirred is sitting suspended in the water.

I know bleach is recommended but I don't really have a choice. It's very expensive here after the pandemic and hit or miss whether it will be in stock, so I recently ordered cal hypo.
 

mknauss

Mod Squad
TFP Expert
Bronze Supporter
May 3, 2014
32,533
Laughlin, NV
The cal hypo should be dissolving unless your CH, pH and/or TA are very high.
Can you post a full set of test results like Maddie asked above?
 

JCD3nton

Member
Jul 6, 2020
15
laredo
Home Depot in Laredo shows lots of liquid chlorine in stock. Normal price.
Oh man, don't get me started on that. :cry:

I thought I had found a good cheap source of chlorine at home depot/lowe's and bought a big stash of it. It ended up being completely wasted money because the stuff barely touched chlorine levels (like 3ppm for a jug that should have added 12). I'm pretty sure their stock has just been sitting there since even before the pandemic and degraded and lost its potency. After losing $40 on it, I don't really trust them as a source anymore. Hence ordering the cal hypo.
 

YippeeSkippy

Mod Squad
LifeTime Supporter
Jan 17, 2012
14,431
Evans, Georgia
That's why we always tell people to check those manufacturing dates... get it no older than 3 months. I'm so sorry you experienced that.

Buy from stock inside and not stored out in the heat/light of the garden center.
 

JCD3nton

Member
Jul 6, 2020
15
laredo
Test results:

TA: 50-75
CYA: 25-30 (was keeping low until every bit of black algae is gone)
PH: 7.5

FC: not sure, I mixed up the cal hypo granules that were sitting on the bottom so let's see if they finish dissolving

CH: 725, first time I've done this test, may need to redo it. It seemed like the test had a "purple endpoint" but when I came back 10 minutes later the water was blue. Also reading that copper can interfere with this test.
 

JoyfulNoise

TFP Expert
Platinum Supporter
May 23, 2015
17,213
Tucson, AZ
Test results:

TA: 50-75
CYA: 25-30 (was keeping low until every bit of black algae is gone)
PH: 7.5

FC: not sure, I mixed up the cal hypo granules that were sitting on the bottom so let's see if they finish dissolving

CH: 725, first time I've done this test, may need to redo it. It seemed like the test had a "purple endpoint" but when I came back 10 minutes later the water was blue. Also reading that copper can interfere with this test.
The Black Algaecide from In The Swim adds copper in the form of the inorganic salt copper sulfate pentahydrate (CuSO4 • 5H2O). It will not cause an FC demand. If you are losing that much chlorine overnight, your pool has an algae problem. The purple endpoint of the CH test is because your water is contaminated with copper metal, the copper interferes with the CH test. You need to perform the Fading Endpoint test procedure where you add 5 drops of R-0012 before adding the R-0010. That's probably not cal-hypo granules but more likely calcium scale forming from the cal-hypo reacting with the high CH pool water.

If your FC demand is as high as you claim (losing 10ppm in less than 12 hours), then your pool has an algae problem. That has to be fixed first with a SLAM and then you can move on to dealing with the copper which, during a SLAM, will likely cause stains on your plaster.
 

JCD3nton

Member
Jul 6, 2020
15
laredo
If your FC demand is as high as you claim (losing 10ppm in less than 12 hours), then your pool has an algae problem. That has to be fixed first with a SLAM and then you can move on to dealing with the copper which, during a SLAM, will likely cause stains on your plaster.
I really, really don't think algae is doing this. In the past, I've neglected the pool enough and dealt with enough algae blooms to have a good idea about the chlorine demands for a given amount.

A couple of days before I added the algaecide, the pool was in good shape, clear, losing minimal chlorine overnight (unlike a green algae bloom, the black algae wasn't eating much chlorine). Shocked it when it was already in good shape, then let FC drop to 5ppm and added the algaecide.

Ever since adding the algaecide, the water seems completely unable to hold chlorine, despite no visible algae and the black algae historically not affecting chlorine levels much.

I added another 10ppm a little while ago and it just seems to be . . . gone. I've never seen my pool behave like that when the water is clear. For it to be algae, it's behaving as if there was a an opaque dark green algae bloom, that's the only time my pool has ever used chlorine like this. I think there has to be another solution.

I'm worried about this happening if I add a bunch of chlorine:

 

mguzzy

Gold Supporter
Jul 8, 2015
2,196
OV, CA
wait a minute.....have we asked or have you told us yet WHICH product of algaecide you used???
Yeah she said she used "the InTheSwim black algaecide," in the first post. I would do a OCLT to see if the Cl loss is organic or not as Marty suggests. Then move from there. If you are worried the pool will turn green, then a water exchange is the only way to get the copper out.

I never read how you are testing your pool. What test kit are you using?