Getting rid of Phosphates cured my 5yr standoff with black algae

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A

acroy

0
May 11, 2010
205
Dallas TX
Wanted to share
I documented my issue here:

VERY SAD: Return of Black Algae after SLAM

The Setup: SWG Gunite pool, plaster is 13yrs old, well cared for. But some areas of degrading tile grout esp around skimmers. Typical reading before SLAM (I kept it pretty consistent): FC 5 CC 0 pH 7.7 TA 70 ch 400 CYA 80 Salt 3000 Daily sweeping/skimming. I do 100% of the maintenance and use...
www.troublefreepool.com www.troublefreepool.com
Small specs of black algae on the plaster and grout. Pool had been SLAMMED to 100ppm for 20 days, FC kept elevated etc. Pool always passed the OCLT and CC always 0. Dealing with this for the last 5yrs. Frustrating as everything is 'fine' but for the accursed specs of black algae

The algae started coming back this spring as usual, soon as water got above about 60F, despite holding FC at 10-12ppm. Which seems excessively high already. I did a ton of reading and honed in on phosphates. Experts say it's irrelevant, others claim getting rid of the phosphates cured their issues.

Nothing to lose except a few $$, so I bought a couple test kits and verified the pool was at about 600ppb phosphates. Present but not high by any means. Purchased a quart of Orenda PR-10,000, did the math, threw in half a quart. Flocculate it did. I let it work and after a couple days I swept as much as I could into the drain, then backwashed, disassembled & 100% cleaned the filter, put it all back together. Maintained 10-12ppm FC throughout.

Here to tell you, the black algae is GONE. All the little pinheads in the gunite, and bits of algae in grout imperfections, vanished within a few days. Like it was never there. I've let the FC drift down to 5-7ppm and all is well.

YMMV. I am super happy :) Good luck and I hope this may help someone dealing with a similar maddening issue.
 
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Awesome. Now that you have it cleared up, what is your target FC going to be.

Note that I have a similar CYA as you and I run my FC at 7-10 with no issues, since I want to make sure I never have algae and never get close to the minimum FC.
 
jdang307 said:
I know there are some who say it’s not necessary
Click to expand...
We say it’s not necessary for most. Which it isn’t. There are of course those special circumstances that don’t fit the rule. The problem with that is all the newbs coming in grasping for straws that they too could have the $50 fix that the pool store has already swore to.

It a slippery slope to give an overwhelmed newbie a false sense of hope when statistically speaking they have no phosphate concerns.
 
acroy said:
Wanted to share
I documented my issue here:

VERY SAD: Return of Black Algae after SLAM

The Setup: SWG Gunite pool, plaster is 13yrs old, well cared for. But some areas of degrading tile grout esp around skimmers. Typical reading before SLAM (I kept it pretty consistent): FC 5 CC 0 pH 7.7 TA 70 ch 400 CYA 80 Salt 3000 Daily sweeping/skimming. I do 100% of the maintenance and use...
www.troublefreepool.com www.troublefreepool.com
... Pool had been SLAMMED to 100ppm for 20 days, FC kept elevated etc. ...
Click to expand...

"Pool has been slammed to 100ppm for 20 days..."

Is this true or a mis-type? In no way would TFP condone an FC of 100ppm. Even with a CYA of 80, SLAM Process level is 31ppm.
 
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proavia said:
"Pool has been slammed to 100ppm for 20 days..."

Is this true or a mis-type? In no way would TFP condone an FC of 100ppm. Even with a CYA of 80, SLAM Process level is 31ppm.
Click to expand...
Bible truth. I had previously done a SLAM at 35ish which had no effect. Did some reading on the nasty black stuff and decided to go bananas. Threw out all our towels, toys, bathing suits, replaced the tools, nuked the pool filter & cleaner in 200ppm trash can for a week....
 
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proavia said:
"Pool has been slammed to 100ppm for 20 days..."

Is this true or a mis-type? In no way would TFP condone an FC of 100ppm. Even with a CYA of 80, SLAM Process level is 31ppm.
Click to expand...
I have a reoccurring black algae problem that is getting worse. I would like try Acroy’s high slam method and phosphate treatment but want to know the risks of using a higher chlorine level to my pool and equipment than what the slam level recommends. I am a newbie and have read all the pool school articles and postings on black algae, Cyanobacteria. Thank you
 
aqua mango said:
I have a reoccurring black algae problem that is getting worse. I would like try Acroy’s high slam method and phosphate treatment but want to know the risks of using a higher chlorine level to my pool and equipment than what the slam level recommends. I am a newbie and have read all the pool school articles and postings on black algae, Cyanobacteria. Thank you
Click to expand...
It could damage your pool surface.
 
1627676678117.png

Seriously, that sounds like a lot of dumping and praying with little to no science behind it. Certainly not the TFP approved method for dealing with black algae.
 
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acroy said:
Wanted to share
I documented my issue here:

VERY SAD: Return of Black Algae after SLAM

The Setup: SWG Gunite pool, plaster is 13yrs old, well cared for. But some areas of degrading tile grout esp around skimmers. Typical reading before SLAM (I kept it pretty consistent): FC 5 CC 0 pH 7.7 TA 70 ch 400 CYA 80 Salt 3000 Daily sweeping/skimming. I do 100% of the maintenance and use...
www.troublefreepool.com www.troublefreepool.com
Small specs of black algae on the plaster and grout. Pool had been SLAMMED to 100ppm for 20 days, FC kept elevated etc. Pool always passed the OCLT and CC always 0. Dealing with this for the last 5yrs. Frustrating as everything is 'fine' but for the accursed specs of black algae

The algae started coming back this spring as usual, soon as water got above about 60F, despite holding FC at 10-12ppm. Which seems excessively high already. I did a ton of reading and honed in on phosphates. Experts say it's irrelevant, others claim getting rid of the phosphates cured their issues.

Nothing to lose except a few $$, so I bought a couple test kits and verified the pool was at about 600ppb phosphates. Present but not high by any means. Purchased a quart of Orenda PR-10,000, did the math, threw in half a quart. Flocculate it did. I let it work and after a couple days I swept as much as I could into the drain, then backwashed, disassembled & 100% cleaned the filter, put it all back together. Maintained 10-12ppm FC throughout.

Here to tell you, the black algae is GONE. All the little pinheads in the gunite, and bits of algae in grout imperfections, vanished within a few days. Like it was never there. I've let the FC drift down to 5-7ppm and all is well.

YMMV. I am super happy :) Good luck and I hope this may help someone dealing with a similar maddening issue.
Click to expand...

Orion7319 said:
It could damage your pool surface.
Click to expand...
thank you... very important to know
 
Some pools are more susceptible to black algae than others, mine is one of them. Here is what I do.

Get a mask and snorkel. You have to get down and close with a wire brush and scrap it off. I also use a bamboo bbq skewer to pick at the spots. Get a 1 or 2 gallon pump sprayer and fill that with LC. Spray those spots with the concentrated LC. The pump sprayer works underwater. Those spots will get a short very high dose. Keep the rest of the pool FC elevated. No need to go on a crazy super high SLAM and risk any damage.

Now go back and repeat step 1.

Now keep FC on the high side for the rest of your life. Target level is your new minimum.
 
aqua mango said:
I have a reoccurring black algae problem that is getting worse. I would like try Acroy’s high slam method and phosphate treatment but want to know the risks of using a higher chlorine level to my pool and equipment than what the slam level recommends. I am a newbie and have read all the pool school articles and postings on black algae, Cyanobacteria. Thank you
Click to expand...
the super-slam did NOT fix my issue, it came right back. getting rid of the phosphates did it

Orion7319 said:
It could damage your pool surface.
Click to expand...
how so? genuinely curious. I could see it bleaching color out of a fiberglass or liner pool, but gunite?
 
UPDATE
so the black spots came back. just a few, maybe 10-20% of what it was. This is with FC still at 10! Tested for Phos and sure enough, it's back up to maybe 250. hmmm, not sure where it's coming from. Pool is heavily used, I guess people may be the source. Will dose it again with the Orenda.

Also, while researching a separate issue with my salt cell (incorrect temp reading) I came across this gem on the Circupool website (linky) (emphasis mine):

"Phosphates and Nitrates that are present in the pool will cause the chlorine demand to rise and/or will consume the chlorine being made by the salt system (Also see page 4). Phosphates are very common. Any Phosphate level near or above 100 parts per billion can greatly increase the chlorine demand in the pool. Any Phosphate level over 200 Part Per Billion will not only consume your chlorine, it will also readily feed algae. To remove phosphates, use commercial grade Phosfree. When trying to lower significant phosphate levels, phosphate products meant for weekly maintenance are usually not effective Nitrates will also rapidly consume your chlorine. If the Nitrate level is high, it is often most effective to drain the pool and refill with new water, being sure to add the necessary amount of salt back to the pool."

So, after 12yrs of pool ownership, phosphate management is now part of my routine. YMMV.
 
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