Black Algae

[crashcop]

I am having a problem killing some annoying Black Algae that has started to grow in my pool.

I have looked at many sites and they provide some useful information for concrete, plaster and other non-vinyl lined pools. Many of the suggestions involve scrubbing with a wire brush and pouring chlorine directly onto the effected areas. Of course, these solutions will not work with vinyl.

My pool is an in ground 12x28, vinyl-lined pool. All of my chemical levels are in balance and the water is clear. My only issue is the stubborn Black Algae that keeps coming back.

I have tried a copper based algaecide and super chlorinating with lots of scrubbing and vacuuming. This works for a day or over night and then it is right back where it was, so I start all over again. I have been using this process for about two weeks now and the stuff goes away and then comes right back.

Any help that you can give me would be appreciated.

Thank you,

Frank

 

[KurtV]

Frank,
You need to post your chemistry numbers to get good help. Please post free chlorine, combined chlorine, calcium hardness, total alkalinity, pH, and, most importantly, CYA. Your CYA level determines the shock level. See the Best Guess chart here to determine the shock level for your pool: Ben's Best Guess Chart

The treatment is to maintain the chlorine in your water at shock level until the visible algae is gone and the pool holds its chlorine level overnight. Test three times a day and add chlorine after each test to return the chlorine to your shock level. You should also brush the visible algae patches frequently. This will help break the algae up so that the chlorine can act on it.

The most likely reason your efforts so far have failed is that you didn't shock to a high enough level or for long enough or, most likely, both. Getting rid of this will take diligence, persistence,and patience.

 

[crashcop]

Kurt,

Thanks for the quick response. Sorry it took a full day to respond to your question. I hope that I have covered everything below.

My water chemistry levels are as follows:

Hardness 500
Total Chlorine 1
Free Chlorine 3
PH 7.2
Alkalinity 100
CYA 100

I have a 12 x 28 vinyl lined in ground that goes from 4-6 feet (approx. 12,500 gallons). I have a Hayward Perflex extended cycle DE filter with a 1.25 hp pump. A 150,000 BTU Coppertherm heater is also plumbed in-line.

I have been doing some reading on the site and it looks like the way to go is the “BBB” method. I went out today and picked up some bleach and will use that based on what your thoughts are.

Thanks again for all of your help.

Frank

 

[KurtV]

OK,with your high CYA your shock level is 25 ppm. It will take about 4.6 gallons of bleach to raise your chlorine by 25 ppm. Once you're at 25 ppm start testing 3x per day (first thing in the morning, at noon or when you get home from work, and last thing in the evening). Add enough chlorine after each test to return the water to 25 ppm. Keep this up until the algae is gone and the water holds its chlorine overnight; that is, the chlorine level at the morning test is the same as when you left it the night before.

Once you're rid of the algae, keep your chlorine between 8 and 15 ppm to prevent recurrence (I'd stay closer to the 15 ppm end of that range). The other alternative, which I would not undertake until after the algae is under control, is to lower your CYA by draining part of your water and refilling.

This problem occurred because you has insufficient chlorine for your level of CYA. That happened in part because your CYA is so high. Your CYA is high because you've been using stabilised chlorine as your main chlorine source (tri-chlor pucks, I bet). I recommend you ditch the pucks and use bleach as your chlorine source; even if you decide to lower your CYA. Save the pucks for when you're going on vacation or need to add CYA (it will go lower, albeit very slowly, through splashout and backwashing).

Good luck and happy algae killing.

 

[crashcop]

Kurt,

The bleach is in (6% on sale at family dollar $2.00 for 1.5 gal), pool is vacuumed and brushed and my algae slaughter is under way.

I have another question or two, if you don’t mind answering.

First, I guess that having as low a CYA level as possible is the way to go? I remember reading a “normal” range for this being around 30, but I guess the lower the better. You were right about he type of chlorine; I have used both sodium dichlor and trichlor.

Second, you said once the black stuff is gone and I am holding 25 ppm, I should go down to 8-15 ppm, leaning more toward 15. Is this OK to swim in? Again, with “normal” being near 3 ppm. I know that the wife wants to get back in as soon as possible and the time that we are up around 25 ppm and she can’t use it will be killing her.

I also guess from doing some research on here that I should not worry too much, about PH and the other stuff while the super-chlorination is going on.

Thanks again, your help has really shed some light on a topic that I thought I had a good handle on.

Frank

 

[KurtV]

Kurt,


I have another question or two, if you don’t mind answering.

First, I guess that having as low a CYA level as possible is the way to go? I remember reading a “normal” range for this being around 30, but I guess the lower the better. You were right about he type of chlorine; I have used both sodium dichlor and trichlor.
With no or very low levels of CYA (say less than 10 ppm) your chlorine is quickly destroyed by sunlight and you'll have a very hard time keeping chlorine in your water. While you don't need much chlorine at that level of CYA (1-3 ppm) the sun just eats it too quickly to keep any in the pool. With very high levels of CYA (say 90 ppm or more), your chlorine will be well protected from the sunlight but less able to do its job as more will be bound up with the CYA. You can operate like that but you have to keep 8-15 ppm (for 100-200 ppm CYA) or risk algae and an unsanitary pool. Without an SWG, I'd guess most people here shoot for something on the order of 30-50 ppm (though there are a plethora of opinions). I try to keep mine between 30 and 40 ppm.

Second, you said once the black stuff is gone and I am holding 25 ppm, I should go down to 8-15 ppm, leaning more toward 15. Is this OK to swim in? Again, with “normal” being near 3 ppm. I know that the wife wants to get back in as soon as possible and the time that we are up around 25 ppm and she can’t use it will be killing her.
"Normal" for your level of CYA is 8-15 ppm. Any lower and you will get algae and your pool will be unsanitary (at 3 ppm you will most assuredly be in the algae farming business again). Any higher and you may introduce some risk associated with chlorine exposure (though there's been debate here on that).

I also guess from doing some research on here that I should not worry too much, about PH and the other stuff while the super-chlorination is going on.
You'll have a tough time testing your pH with the chlorine level that high. The chlorine bleaches out the reagent.

Thanks again, your help has really shed some light on a topic that I thought I had a good handle on.

Frank

If you take one thing out of this experience make it this: The required level of free chlorine is a function of the level of CYA in your water. See the Best Guess Table for details (link above).

 

[Guest]

Hardness 500
Total Chlorine 1
Free Chlorine 3
PH 7.2
Alkalinity 100
CYA 100

Am I the only one that caught this? It is impossible for the total chlorine to be less than the Free Chloirne. By definition total chlorine = free chlorine + combined chlorine. How were these test results obtained? Also, black algae takes a lot of pool neglect to happen. Sorry to say it but it's true. It takes a long time of not enough chlorine for it to take hold. If copper has not worked then I would recommend a sodium bromide black algae treatment such as Proteams Mustard and Black Magic and a LOT of chlorine. By temporarily converting your pool to bromine you remove the stabilization effects of the high cyanuric acid levels and that, combined with a LOT of brushing to break open the hard cell casing on the black algae might kill it. Be aware that since the pool wont be stabilized as long as it is a bromine pool your santizer will be burned off by sunlight very quickly and you will be needing to add chlorine several times a day to keep the bromine levels up.
Hope this helps.

 

[KurtV]

Am I the only one that caught this? It is impossible for the total chlorine to be less than the Free Chloirne. By definition total chlorine = free chlorine + combined chlorine. How were these test results obtained? Also, black algae takes a lot of pool neglect to happen. Sorry to say it but it's true. It takes a long time of not enough chlorine for it to take hold. If copper has not worked then I would recommend a sodium bromide black algae treatment such as Proteams Mustard and Black Magic and a LOT of chlorine. By temporarily converting your pool to bromine you remove the stabilization effects of the high cyanuric acid levels and that, combined with a LOT of brushing to break open the hard cell casing on the black algae might kill it. Be aware that since the pool wont be stabilized as long as it is a bromine pool your santizer will be burned off by sunlight very quickly and you will be needing to add chlorine several times a day to keep the bromine levels up.
Hope this helps.

Good catch, Waterbear. I was focused solely on the CYA number.

crashcop,
How was your water tested? Do you have a good test kit?

I wouldn't abandon the chlorine regimen until you've given it a chance to work.

 

[crashcop]

Looking over my notes it appears that I transposed those two numbers when composing the post here. Thanks for the heads up.

I am continuing the chlorine regimen. I took a reading this morning and will run home shortly to get a mid day reading.

My neighbor had a similar problem last season and used a product called “Black Treat”. He said that he had to keep his chlorine levels up and then added this stuff. Have you heard of it before?

Yes, Waterbear, you are right about the neglect. I was out of town for about two weeks and left pool care in another person’s hands. I have learned my lesson and what happens from even a short time of neglect.

Thanks again to everyone for your help. The information that I received from you guys as well as from surfing the site has been invaluable.

Frank

 

[KurtV]

I don't know what's in Black Treat and the MSDS doesn't list the ingredients. Does your neighbor still have the bottle? Regardless, I wouldn't use it yet. While black algae (if that's what you have) is very stubborn, it's not nearly as difficult to get rid of on a vinyl liner as it is on plaster. Stay the course, at least for a few days.

 

[crashcop]

Thanks

He was going to see if he still had some of the stuff and let me have it. If he does, I will let you know what is in it. I do agree with you that I should stay with what I have started and see what happens. Much of the algae was gone this afternoon and it looks like this will be the way to go. I plan on brushing some more as soon as I get home.

Thanks again,

Frank

 

[Guest]

United Chemical is notorious for listing as little as possible in their MSDS but the majority of their products are either inorganic ammonai or sodium bromide. I suspect the Blacktreat is inorganic ammonia since the MSDS says that it can release ammonia fumes on combustion. If you have to raise the pH before you use it and follow it with a chlorine shock it is inorganic ammonia. IMHO, this works better on green and mustard algae than black. I prefer sodium bromide for black algae.

 

[gonefishin]

Hi

Could you post pictures of the black algae in your pool? That will not only help these guys and gals assist you...but it could also help others in identification of black algae in their pools.

Also...would it be possible to get a couple of sample of this algae? If so...but some of it into some small glass jars (like baby food jars) and then we could do a few experiments on it.

If you have a plastic bottle with a small tip on the end you can use that to "suck" up the sample of algae. Squeeze the air out of the bottle while above water, then once you swim down to the algae slowly (slowly) move you hand toward the algae. Once your very close let the water and algae sample get sucked into the bottle as you release pressure on it.

thanks,
dan

 

[crashcop]

Hello,

The pictures will be no problem, although most of it has started to disappear.

Now for the samples...I have to laugh...is this the welcome initiation for the new guy on the site...LOL?

If you think it might help someone else down the road, I would be more than happy to do it, but I do have to laugh and I am not telling anyone (friends, family, neighbors) when I am going to swim down with my airless bottle and suck on the algae. LOL

At this point, I really don't think I would be able to obtain a good enough sample anyway.

Thanks again for everyone's help.

Frank

 

[crashcop]

Hello everyone,

It looks like the treatment is going along well. Most of the offending algae are gone with just a small patch left. More vacuuming and brushing tonight, as that seems to really be the second part of the 1-2 punch.

Just an FYI about Black Treat. My neighbor was able to dig up a 3lb canister of it and it says that the Active Ingredient is Sodium Bromide 48.5% and Inert Ingredients 51.5%.

The directions say to brush the algae then add 3lbs of Black Treat per 20,000 gallons directly to the visible algae. Then add 2.4 lbs of a fast dissolving chlorine to bring the level up and then keep the chlorine level at 3.0 ppm. They also say to pour the chlorine directly onto where the algae are as well.

Of course, they recommend brushing and they have some special warnings about brushes and types of surfaces and chemicals and types of surfaces. The directions above give the Readers Digest version of the application process.

Don’t worry, I am sticking to what I have already started!

Thanks again,

Frank

 

[gonefishin]

Glad to hear that your winning the fight!


Initiation? No :lol:

I just thought it may help others with proper identification if they think there is something similar in their pool.


keep up the good work!

dan

 

[crashcop]

Dan,

Just kidding about the initiation part. I just thought it would be funny seeing me diving down trying to suck up some algae in a bottle.

As far as the pictures go, I am going to shoot some tonight and try to get them on here tomorrow morning. I am off tomorrow so I should have them up before noon my time.

Thanks for the encouragement.

Frank