SLAMming a clear pool

bmj0928

Bronze Supporter
Jun 25, 2020
48
Pittsburgh, PA
This thread is my SLAM thread.

This is my first SLAM. Prior to this, I drained 45% of my water to get my cya to 50.
My pool was crystal clear to start, but I decided to SLAM because I was at such a high CYA for so long, another thread said that I was on the verge of an algae bloom because my sanitizer was rendered useless, and I was not at minimum FC levels for quite sometime.

Started the SLAM last night at 9:30pm.
Starting numbers:
FC=0.5
CC=1
pH = 7.2
TA=90
CH=325
CYA=50
I had to keep adding more bleach than pool than Pool Math suggested to get to slam level, testing 30 minutes after each addition. By 11:00pm I was at FC=22
CC=0.5
at midnight pm:
FC=19.5
CC=0.5
I had failed the OCLT in less than an hour! I added 44oz of bleach, and went to bed.
8:00am:
My wife commented, "Wow, the pool looks even clearer and more beautiful!" How can an already crystal clear pool look clearer? Some of the stubborn "stains" in the corners were gone, and what I thought was general iron staining (yellow streaking on the sloped, painted bottom) was also gone. I now think I may have had a mustard algae problem.

OCLT test result:
FC=4
CC=0
Not exactly sure what the drop over night was, but it doesn't matter.

So, the SLAM continues until the OCLT is less than 1.
 

setsailsoon

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LifeTime Supporter
TFP Guide
Oct 25, 2015
3,470
Stuart/FL
28,

Welcome to TFP. Looks like you're off to a great start! Looks like you definitely needed a SLAM. There are 3 conditions that are required to complete. I've added the video at the end of my post. Keep with it until you meet all three and your pool will sparkle from now on..

Please do keep us updated and photos would be great.

Chris

 
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bmj0928

Bronze Supporter
Jun 25, 2020
48
Pittsburgh, PA
Mid-SLAM photos, as requested, @setsailsoon. Notice the yellow/brown around the returns and skimmer? This comes off with vitamin c pills, but I don't think it's iron. I think it might be algae.
 

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duraleigh

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In The Industry
Apr 1, 2007
34,426
Sebring, Florida
Hard to tell from the pics. I would unscrew the ring holding the return and then wipe it down with a rag soaked in bleach. If it disappears, it was algae
 
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bmj0928

Bronze Supporter
Jun 25, 2020
48
Pittsburgh, PA
I decided to buy some Scotch Brite heavy duty scour pads and wipe down my pool. Lo and behold, it removed the dark yellow staining from my returns and skimmer. It also removed staining on my pool bottom and walls that I thought was permanent. I cleaned my waterline tiles, and they look like new. And then... And then I decided to remove my light and see what was growing behind it. Ugh... I released a forest of yellow "feathers" that looked like something you'd find in a farm pond in the middle of August. Disgusting! And the smell!!! So, now my water is no longer clear. It got cloudy.

FC = 17.5
CC= 0.5.
 

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Donldson

TFP Expert
LifeTime Supporter
Jun 12, 2009
4,587
NW Ohio
You're finding what is actually very common: what most people think is a clear and balanced pool oftentimes is not. Algae hiding and slowly eating away at chlorine. What sometimes appears as clear water is harboring just enough algae to not set off the alarms of the casual pool owner. TFP helps clear that up, but also helps owners gain a better understanding and recognition of their water. Given time you'll be able to notice when the water loses just a little luster, warning you of an issue long before even a hint of green is visible.
 

bmj0928

Bronze Supporter
Jun 25, 2020
48
Pittsburgh, PA
Much lower FC drop this morning, compared to the 18+ drop the night before. A lot of grayish "dust" settled to the bottom overnight, and the skimmer sock turned a funky blue-green color.
FC=12 (loss of 8 overnight)
CC=0.5 (barely...there was only the slightest hint of pink that 1 drop cleared up)

Incidentally, after vacuuming yesterday evening, I had a moment of panic when one of the swivel nuts for the hand knob on my filter basket cover broke. A long nose vice grip is an adequate replacement while I wait for the new parts to arrive.
 

Richard320

TFP Expert
LifeTime Supporter
Jan 6, 2010
23,930
San Dimas, CA (LA County)
Much lower FC drop this morning, compared to the 18+ drop the night before. A lot of grayish "dust" settled to the bottom overnight, and the skimmer sock turned a funky blue-green color.
FC=12 (loss of 8 overnight)
CC=0.5 (barely...there was only the slightest hint of pink that 1 drop cleared up)

Incidentally, after vacuuming yesterday evening, I had a moment of panic when one of the swivel nuts for the hand knob on my filter basket cover broke. A long nose vice grip is an adequate replacement while I wait for the new parts to arrive.
Is that blue-green color reminiscent of the scotchbrite pad? They do wear down.
 
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bmj0928

Bronze Supporter
Jun 25, 2020
48
Pittsburgh, PA
Today, looking extremely clear:
FC= 18 (overnight loss of 4)
CC= 0.5

Seems like OCLT loss results are reducing by half each night. Hopefully I can end the SLAM Sunday, because I'm starting to need to conserve R-0871. I ordered more, but it might not get here before I run out.
 
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CrystalRiver

Well-known member
Jun 19, 2020
289
Massachusetts
Today, looking extremely clear:
FC= 18 (overnight loss of 4)
CC= 0.5

Seems like OCLT loss results are reducing by half each night. Hopefully I can end the SLAM Sunday, because I'm starting to need to conserve R-0871. I ordered more, but it might not get here before I run out.
When running low, I have diluted my sample 50% (5 mL pool and 5 mL chlorine-free water) and then 1 drop = 1 ppm. Not accurate enough to officially OCLT, but at least it keeps you in the ballpark. I've even done 2.5 mL pool, 7.5 mL chlorine-free with 1 drop = 2 ppm. I use a child's medicine dosing syringe to make precise measurements easy.
 

bmj0928

Bronze Supporter
Jun 25, 2020
48
Pittsburgh, PA
Was hoping to end the SLAM today, but had an OCLT of 3 last night... And so it goes. Yesterday was a very windy, rainy day, though, and a lot of leaves blew nto the pool.

I really believe I'm dealing with a long established mustard algae problem. I thought I had iron staining in my pool. The staining was sort of streaky, in general, mostly noticable in low light, with some heavily stained spots that were always visible. All of this is fading the longer I slam. The heavy stains are gone. The general streaking is going, and fading more a few hours after each brushing / vacuum.

I got a stainless steel brush for my pool bottom (epoxy painted plaster). It doesn't seem to get the discoloration up when I brush, but I think its making a difference. From what I've read in these forums, it's breaking down the biofilm so the NaClO can work. The pool bottom looks cleaner than ever.