Just treated for phosphates.. and still have phosphates?

aqua mango

Silver Supporter
Jun 10, 2015
37
Waikoloa Hawaii
Advice please,
I just treated my pool recently for yellow and black algae, ( Cynobacteria) as well as high phosphates. (Followed instructions from TFP pool school and used Orenda Pr 10,000 for phosphates as instructed on their website)
My FC is still coming down from the highs recc here for treating yellow algae. I retested my phosphates today using the AquaChek one minute Phosphate test and it is still reading in the High 200 level. I am disappointed due to hoping my phosphate level would read 0. I am trying to starve the black algae off and know it feeds on the phosphates.
My question is:
Do I retreat my pool with Orenda PR 10,000 until I finally get a 0 phosphate reading? Also should I be doing a monthly or weekly maintenance dose of Orenda PR 10,000 ? I get lots and lots of silt blown into our pool besides bugs... not too many leaves though.
Thank you
 

Texas Splash

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Aloha! :wave: Let's be sure we're on the same page about a few things for best advice. You mentioned potentially having yellow (Mustard?) and Black algae. Did you first perform a SLAM Process through its entirety? That must always be step #1. As you may know, Black algae is particularly persistent due to its ability to root itself into plaster, so being aggressive (and consistent) with brushing and the proper elevated chlorine SLAM level is a must during the SLAM Process. Once it's growing, you're not going to starve it to death with Orenda.

So let us know where you are in regards to the SLAM Process and we'll go from there.


 
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Bperry

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Aug 20, 2020
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Advice please,
I just treated my pool recently for yellow and black algae, ( Cynobacteria) as well as high phosphates. (Followed instructions from TFP pool school and used Orenda Pr 10,000 for phosphates as instructed on their website)
My FC is still coming down from the highs recc here for treating yellow algae. I retested my phosphates today using the AquaChek one minute Phosphate test and it is still reading in the High 200 level. I am disappointed due to hoping my phosphate level would read 0. I am trying to starve the black algae off and know it feeds on the phosphates.
My question is:
Do I retreat my pool with Orenda PR 10,000 until I finally get a 0 phosphate reading? Also should I be doing a monthly or weekly maintenance dose of Orenda PR 10,000 ? I get lots and lots of silt blown into our pool besides bugs... not too many leaves though.
Thank you
What are you using to test the water for the other levels? Would need to know what your chlorine levels and remove the algae before worrying about phosphates.
 

aqua mango

Silver Supporter
Jun 10, 2015
37
Waikoloa Hawaii
Aloha! :wave: Let's be sure we're on the same page about a few things for best advice. You mentioned potentially having yellow (Mustard?) and Black algae. Did you first perform a SLAM Process through its entirety? That must always be step #1. As you may know, Black algae is particularly persistent due to its ability to root itself into plaster, so being aggressive (and consistent) with brushing and the proper elevated chlorine SLAM level is a must during the SLAM Process. Once it's growing, you're not going to starve it to death with Orenda.

So let us know where you are in regards to the SLAM Process and we'll go from there.


Yes, I followed exactly the slam process for SWG based on my pools CYA then the elevated slam for yellow algae. During this time I regularly brushed my pool using a wire brush on the black algae spots and breakouts as well as used a trichlor puck in a puck holder to rub on the black algae spots, numerous times a day over a 5 or 6 day period. The black algae spots have been in my pool for probably some years, (we just moved back home this past year and I have been trying to get a handle on improving our pool).
The black algae up to now has showed very little regression in its appearance and I have not been successful in removing any of the spore heads as others have mentioned. Maybe it is a little bit less vivid but not much. I have read that black algae, (cyno bacteria) can become resistance to the chlorine I am using but am hoping it will respond by dying if I can get rid of the phosphates. Am I understanding this correctly? I have kept all my records of treatment for the usual SWG slam and yellow algae slam I just completed in my pool notebook but didn't add them to my TFP record but I followed the info to the T.
 

Texas Splash

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Jun 22, 2014
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Thanks for the details. That helps. In your case, I'm going to ask for the assistance of @JoyfulNoise who might be able to help us determine the best way forward with plaster that has been neglected for a significant amount of time. More aggressive treatments may be required. Standby for more .......
 

Leebo

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Jul 21, 2011
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Keep in mind you’ll never get zero phosphates, especially if you’ve got algae in the water. There’s phosphates in the cells of the algae that get “released” when the algae dies. Kill the algae with chlorine and frequent brushing……then we’ll talk about phosphates.
 

JoyfulNoise

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May 23, 2015
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Tucson, AZ
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Are you absolutely sure it’s black algae? Can you scrape it with your fingernail and smear it on some paper. Does it leave a dark green trail (black algae isn’t black, it’s dark green)?

Algae never becomes “resistant” to chlorine, no biological organism does. What black algae does is grow a thick cell wall layer that slows down the chlorine from entering the cell. All algae can be killed, it’s just a matter of time.

If the plaster is old, porous and contaminated with algae, it’s going to take a long time to fix. You’ll need to SLAM the pool and then keep FC levels at the high end as a standard practice. The algae will eventually die over time.

But many people think they have black algae when, in fact, it’s organic staining or metal staining. That’s why I asked - are you absolutely sure it’s black algae??
 
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aqua mango

Silver Supporter
Jun 10, 2015
37
Waikoloa Hawaii
Are you absolutely sure it’s black algae? Can you scrape it with your fingernail and smear it on some paper. Does it leave a dark green trail (black algae isn’t black, it’s dark green)?

Algae never becomes “resistant” to chlorine, no biological organism does. What black algae does is grow a thick cell wall layer that slows down the chlorine from entering the cell. All algae can be killed, it’s just a matter of time.

If the plaster is old, porous and contaminated with algae, it’s going to take a long time to fix. You’ll need to SLAM the pool and then keep FC levels at the high end as a standard practice. The algae will eventually die over time.

But many people think they have black algae when, in fact, it’s organic staining or metal staining. That’s why I asked - are you absolutely sure it’s black algae??
Thank you for responding and although I can not scrape off any black algea and smear it I have seen the algae cluster flare up, (become more alive, look more pronounced, larger ) at times when I was busy and my chlorine got too low and my pool temp was high. I will submit photos once the wind calms down again and the water is calm.
I have followed the complete TFP steps for treating Mustard Algae and Black Algae by first slamming my pool and holding FC level (based on my CYA) until no lost overnight then raising my FC to the Mustard Algae level of 46 and holding for 24 hrs then for Black Algae keeping my FC between 6 and 31 until the Black Algae is gone, (this is the step I am now). I am also using a trichlor puck in a puck holder to rub on the different black algae spots after wire brushing them a couple of times a day. I have been in the Black Algae part of the treatment now for 12 days. 3 days ago I also treated for high phosphates using Orenda PR 10,000 as per their website and throughout this process I have been brushing my pool walls and vacuuming to waste. I have read that cyanobacteria (black algae) can become resistance to Hypochlorous but not to Chlorine dioxide but that Chlorine dioxide is difficult to use (and to get) due to it not being stable in sunlight and is expensive. Have you had any experience using Chlorine dioxide for Black Algae? Also should I keep treating for phosphates and does black algae die without phosphates? I haven't seen any improvement with what I have been doing so far on the black algae. If you are still thinking that my FC should kill the Black Algae what FC level should I stay at? My pool is 27,000 gallons Thank you
 

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aqua mango

Silver Supporter
Jun 10, 2015
37
Waikoloa Hawaii
Just for kicks as a test, do you have some dry acid (PH Down) handy? Try placing some of that in a thin sock and rub it on that black stain. Let's be sure it's not copper.
I did have some pH down so just did what you suggested. Nothing changed. It doesn’t look like a stain to me but a growth. I will post some photos now under Joyfulnoises post. Thank you
 
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aqua mango

Silver Supporter
Jun 10, 2015
37
Waikoloa Hawaii
Are you absolutely sure it’s black algae? Can you scrape it with your fingernail and smear it on some paper. Does it leave a dark green trail (black algae isn’t black, it’s dark green)?

Algae never becomes “resistant” to chlorine, no biological organism does. What black algae does is grow a thick cell wall layer that slows down the chlorine from entering the cell. All algae can be killed, it’s just a matter of time.

If the plaster is old, porous and contaminated with algae, it’s going to take a long time to fix. You’ll need to SLAM the pool and then keep FC levels at the high end as a standard practice. The algae will eventually die over time.

But many people think they have black algae when, in fact, it’s organic staining or metal staining. That’s why I asked - are you absolutely sure it’s black algae??
Please see attached photos of pool wall(2 photos of the same spot) and pool light ledge. The fine speck is silt floating on the water. I have 5 black algae outbreaks about this size then probably hundreds of small spots. I just tried the pH down scrub test on one of the bigger areas without any results.
 

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Bperry

Gold Supporter
Aug 20, 2020
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Your black algae spots look different than mine did. Mine seemed to gather in spots where my plaster has worn away. In fact, those are what brought be to TFP. Mine went away with a normal SLAM. I’ve got no advice other than scrubbing with a stiff plastic brush and chlorine. The stainless brushes just seem to wear away the plaster.
 

aqua mango

Silver Supporter
Jun 10, 2015
37
Waikoloa Hawaii
Your black algae spots look different than mine did. Mine seemed to gather in spots where my plaster has worn away. In fact, those are what brought be to TFP. Mine went away with a normal SLAM. I’ve got no advice other than scrubbing with a stiff plastic brush and chlorine. The stainless brushes just seem to wear away the plaster.
Thank you for responding. Yes I should switch to a hard plastic brush cause I am
Wearing away plaster.
 

Katodude

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Aug 22, 2017
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Take a bamboo BBQ skewer or something similar (a wood golf tee works too). Get in there with a mask and snorkel and see if you can pick at it. If it flakes off and you see some green underneath it is most likely black algae. Pick off as much as you can either with the skewer or a pool wire brush.

Here is the pro move. Get a 1 or 2 gallon pump sprayer with chlorine and go spray those sections right after you pick off the upper layers. Repeat the whole process the next day. Then run elevated FC for a few weeks.
 
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