OCLT good…but algae still in pool

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300winmag

Gold Supporter
Aug 2, 2016
228
Dallas, TX
in ground pool. Full tx sun.
Pebble finish
SWG (currently off)
Spa overflow, 3 fountains and 2 vertical bubble columns. All running during the SLAM
CYA is 50
Ph of 7.2 at start of SLAM
Maintaining SLAM FC of 20ppm.

I lost 1.0 ppm of FC overnight, but I still have yellow mustard algae on the walls and floor. So, the SLAM will continue.

I’ve been at this for several days now and I’m shocked how much Crud I still stir up when brushing.
My question is, at some point will the SLAM rid the pool of the stuff I’m stirring up? Or maybe the filter is supposed to catch it?

Thanks
 
300winmag said:
My question is, at some point will the SLAM rid the pool of the stuff I’m stirring up? Or maybe the filter is supposed to catch it?
Click to expand...
Yes. How often are you brushing? Did you scrub behind the light? Under the drain covers?

Do me a solid and retest your CYA using these instructions:
www.troublefreepool.com

CYA - Cyanuric Acid Test

Cyanuric acid (CYA) is the chemical name for the product commonly called “pool water stabilizer” … Read more…
www.troublefreepool.com www.troublefreepool.com
 
Brushing at least 4 times per day
Scrubbed the light….not the drains!

Retested cya w this method and got 50. It obscured at 40, + 10. So 50.
Before i was just looking when the dot disappeared, which was at 50. So maybe I lost 10ppm of cya during this?
 
300winmag said:
Before i was just looking when the dot disappeared, which was at 50. So maybe I lost 10ppm of cya during this?
Click to expand...
Testing variance. Ignore it. CYA is 50. Strong indirect light is the key to this test. Get those covers off and scrub...PUMP OFF (AT THE BREAKER).
Good job.
 
Still brushing up the dusty crud.


As a general question, if 20ppm FC is good for my CYA level, what makes higher FC not good? Does it just lose potency / effectiveness above a certain level? Does it interact with the CYA making it effective only to a certain ratio?
 
Most FC gets bound to CYA (95-99% dependent on pH, temp etc.) The Active/unbound FC is HOCl. As HOCl is used, CYA releases more, but the % of FC that is HOCl doesn't change.
The % of FC that is HOCl is dependent on the CYA level (pH etc).
SLAM level FC maintains enough active chlorine (HOCl) to kill Algae.
Raising FC won't do any more than SLAM level FC.
It is about MAINTAINING FC that kills the algae, not MORE.
 
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If you've broken the biofilm and allowed chlorine to get to the algae, I doubt the biofilm can recover again that fast. Once daily thorough brushing is usually adequate. Don't want you getting *Pool Brushing Elbow* or anything, ya'know?
The brushing also aids in getting the dead and dying algae into circulation so that the filter can pick it up.

Maddie :flower:
 
YippeeSkippy said:
If you've broken the biofilm and allowed chlorine to get to the algae, I doubt the biofilm can recover again that fast.
Click to expand...
wouldnt this mean that as long as you break the film and there is sufficient FC that the algae should die once agitated? So if you agitate the whole pool once, it should all die and you could clear the pool in a day?

Where does it keep coming from?
 
You will have algae in your water for quite a while as you kill if off day by day. Don't forget it will be hiding in your skimmer, on the weir door, in your pool returns, in the pool light, in the main drain cover, in the autofill, etc. All of those need to be scrbbed and cleaned with chlorinated water. This is a slog but it gets better as you go on.
 
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