A little mustard with my hot dog

Jim Savage

Active member
Jul 5, 2020
34
West Gardiner, ME
So, I believe I have a bit of mustard algae in my pool. I'm preparing to SLAM.

Notably, this is a new pool to us, 20x40 vinyl. Fresh liner a month ago. Pool was filled with 30,000 gallons of lake water that I was trying to balance with test strips. Then I got smart and bought a TF100 kit.

Algae is more like clear, slimy patches and light tan powdery patches, mostly on seams. When I brush even the clear areas, a white powder floats around. Water is pretty darn clear in spite of this, until I brush.

Current values:
FC 2.5
CC 0
CYA 30
CH 300
pH 7.2
TA 140

I'm currently chlorinating with trichlor pucks, mostly because I have them and CYA was already low. I plan SLAMing with liquid. I see that I should SLAM to 12 ppm until complete, then to 19 for 24 hours.

Questions... screw with the ph/ta issue after slam or before?
This is mustard, right?
 
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Jim Savage

Active member
Jul 5, 2020
34
West Gardiner, ME
Thank you, sir! I did in fact peruse the library of pool info. Really helpful stuff. I'm mostly guessing at the mustard, primarily because it isn't green. I figured all that I'll lose is the cost of the chlorine to take it to MA levels but risk losing a lot of time if I don't and it rebounds.

Any thoughts about the high TA. I imagine by the time the SLAM is done, my pH will have corrected some. Not sure if the TA is worth the worry. This is the biggest pool I've ever owned and I am certainly looking to be cautious about what I do to it. Correcting mistakes seems like it can get expensive when you have 30,000 gallons to balance.
 

Wobblerlorri

Bronze Supporter
You take your pH down to 7.2 at the beginning of a SLAM, so you're good there. Don't worry about pH during the SLAM -- it's inaccurate under high levels of chlorine. Likewise don't worry about the TA -- you're laser-focused on FC and CC for now. Just test and adjust as often as you can, and brush, brush, brush.
 

Jim Savage

Active member
Jul 5, 2020
34
West Gardiner, ME
Much thanks. I'm hoping this goes smoothly with no hiccups. The water looks good other than this apparent algae. It's almost unnoticeable so I'm hoping I can SLAM it in a day and not lose a lot of pool usage. I figure I'll pull the ladder in the morning and get to it. I'll likely scrub the ladder down with 50/50 chlorine and water... I don't trust it, with all of its nooks and places for algae to hide. Gives me something to do while the pool is soaking. Hopefully it finishes off in a place that favors a little acid to balance it all out.
 

kellyfair

Gold Supporter
Bronze Supporter
Jun 29, 2016
2,925
Tampa, FL
Jim, SLAM isn’t normally a single day event. However, if you check your chlorine level every couple of hours and dose back to SLAM level, it will go quicker than if you only test 3 or 4 times.

I think I remember an old thread where @Casey went from swamp to perfect in just a few days, but she was testing every hour or two, if I recall!
 

Jim Savage

Active member
Jul 5, 2020
34
West Gardiner, ME
1030 update:

FC12, CC0.

Water is no longer clear after the 0830 brushing and chlorine additions... very mildly milky. I took a pic of what I'm seeing. I can see " reforming " patches, but, it's weird. It's only showing on seams and wrinkles right now. When I brushed this morning I certainly saw the whitish powdery haze float up around the brush. Nothing on the vertical surfaces, minimal on the slopes. I want to call it dust almost, though, that doesn't account for the clear slimy patches originally noted.

Next test in 2 hours. Sun is on 3/4 of the pool now so I expect to see a FC drop.
 

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Jim Savage

Active member
Jul 5, 2020
34
West Gardiner, ME
1230 test. FC 11 CC 0

Adding 121 oz to correct for FC loss

Water remains pretty clear as to say that sitting on the deck by the shallow end I can see the main drain in the deep end pretty clearly. Slight haze in the water. Some signs of... whatever it is settled on the bottom. Time to brush again.
 

kellyfair

Gold Supporter
Bronze Supporter
Jun 29, 2016
2,925
Tampa, FL
Totally not weird. Brushing up the dead stuff so it mixes with the water and goes through the filter is what you want. And keeping your chlorine at SLAM level kills any live stuff, causing the dead stuff to accumulate at seams and wrinkles - normal.

Keep going!
 
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mariane

Bronze Supporter
LifeTime Supporter
May 8, 2012
1,090
Southeast Michigan
Vacuum the settled algae first, then brush. Brushing first will stir up the dead algae and then you have to wait for the skimmer and filter to get it out of the water.
Make sure you slowly sneak up to the dead algae settled on the bottom and then slowly vacuum it up into the filter. No need to vacuum to waste.
Then brush after you've vacuumed. The process will go a little bit faster. :wink:
 
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Jim Savage

Active member
Jul 5, 2020
34
West Gardiner, ME
1430 test

FC 9, CC 0

Adding 187oz to correct FC.

Minimal debris on the floor. I'll probably opt to brush and vacuum at 1630. Or rather vaccum then brush as mariane has suggested.
 
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