Mustard Algae

vlh3

Member
Jul 12, 2023
21
Inver Grove Heights, MN
I have done the SLAM process twice now this season. I have read the article on Mustard Algae... "Mustard algae is a particularly persistent kind of algae, that appears to go away when you SLAM the pool normally, only to reappear as soon as you come back down to normal chlorine levels." This seems to be what is happening in my pool. I began the MA process after my second SLAM.

Couple of questions: Seems like my FC levels drifted down during the MA process, at times it was difficult to maintain, but I always added more liquid chlorine. Since it hasn't always stayed at 19 for CYA of 30, should I extend the 24 hour period?

My test results this morning are: FC 23.5, CC .0, pH 8, TA 120, CH 250, CYA 30. Which brings my CSI to .55. Should I bring the pH down or wait until I'm done with the 24 hour period? My pH during most of the 24 hour period has been at a level within range... I have a few more hours left of the 24 hours. I'm still seeing slight algae drifts on the stairs and some in the deep end. Is this dead MA? I don't want to take any chances of this coming back... this stuff is a PITA! Especially since we have a short season here in Minnesota... and this season, I've been battling algae issues for half the season!

I appreciate your advice!
 
The ph test is invalid at fc levels over 10ppm so disregard that & make no adjustments.
For the initial
SLAM Process did you pass all 3 end of slam criteria before raising fc to MA slam level?

✅ CC is 0.5 or lower;
✅ You pass an Overnight Chlorine Loss Test
AND
✅ The water is clear.
(Crystal Clear w/no algae dead or alive)

If not - go back to regular slam level until then.
 
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Also, after completion of the MA protocols you may want to maintain MA minimum for some time as referenced in the chart
During the slam be sure to do all the things & be very thorough
👇
*Check & scrub every nook & cranny where algae may hide (light niches, steps, drain covers, ladder handrails, skimmer throats/weirs, abandoned lines, autofill, overflow drains, etc.)
*If water can go there, algae can thrive there.
*Run slam level water through all water features & lines for at least a couple hours a day during the SLAM Process.
*Brush & or vac daily (this breaks up biofilms that algae uses to protect itself from chlorine)
*Backwash/clean filter when pressure rises 25%over clean pressure.
 
The ph test is invalid at fc levels over 10ppm so disregard that & make no adjustments.
For the initial
SLAM Process did you pass all 3 end of slam criteria before raising fc to MA slam level?

✅ CC is 0.5 or lower;
✅ You pass an Overnight Chlorine Loss Test
AND
✅ The water is clear.
(Crystal Clear w/no algae dead or alive)

If not - go back to regular slam level until then.
Yes. I did. Perhaps not crystal clear in the deep end. Seemed crystal clear in the shallow end, but after I would finish vacuuming, I could go over the floor and a thin dust of algae would brush up. This stuff that settles on the step and in the deep end, is a yellowish-brown color, kind of very fine sand-like and oily/slimy.
 
Yes. I did. Perhaps not crystal clear in the deep end. Seemed crystal clear in the shallow end, but after I would finish vacuuming, I could go over the floor and a thin dust of algae would brush up. This stuff that settles on the step and in the deep end, is a yellowish-brown color, kind of very fine sand-like and oily/slimy.
The whole pool should be crystal clear with no more recurring algae- dead or alive- before proceeding to the MA protocols.
 
Also, after completion of the MA protocols you may want to maintain MA minimum for some time as referenced in the chart
During the slam be sure to do all the things & be very thorough
👇
*Check & scrub every nook & cranny where algae may hide (light niches, steps, drain covers, ladder handrails, skimmer throats/weirs, abandoned lines, autofill, overflow drains, etc.)
*If water can go there, algae can thrive there.
*Run slam level water through all water features & lines for at least a couple hours a day during the SLAM Process.
*Brush & or vac daily (this breaks up biofilms that algae uses to protect itself from chlorine)
*Backwash/clean filter when pressure rises 25%over clean pressure.
IMG_9664.jpeg
This is what keeps showing up. I have brushed everything yesterday, and vacuumed then backwashed. I put all vacuuming equipment, etc in the pool for about an hour or so as well.
 

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Got any lights, ladders, drains, overflow, auto fill, water features?
Ladder… which I pulled out to brush the wall behind it, brushed the ladder and put it back in. Drain in the deep end, 2 skimmers which I scrubbed, scrubbed the 3 jet fittings. No auto fill or water features.
Algae- keep with regular slam until it all goes away & doesn’t return.
It’s kind of a weird slimy, oily, sticky… not sure how to describe it.
 
Just gotta keep regular slammin- the recurring stuff should get less each day.
You can try to vac it to waste to get the bulk out & add some de to the filter to help capture the finer stuff. After it’s gone raise to ma slam level.
 
Just gotta keep regular slammin- the recurring stuff should get less each day.
You can try to vac it to waste to get the bulk out & add some de to the filter to help capture the finer stuff. After it’s gone raise to ma slam level.
Here’s where I’m at now… FC 18.5 as of 2:20 pm (FC 23.5 at 7:41 am) Looks clear. It’s windy in the pic. I’m still brushing what seems like algae dust from the floor and it’s still settling on the top step. This is pretty much what it looked like after the 1st SLAM. But when I let the FC go to the recommended levels, started having problems again. Should I add more liquid chlorine? IMG_9671.jpeg
 
Here’s where I’m at now… FC 18.5 as of 2:20 pm (FC 23.5 at 7:41 am) Looks clear. It’s windy in the pic. I’m still brushing what seems like algae dust from the floor and it’s still settling on the top step. This is pretty much what it looked like after the 1st SLAM. But when I let the FC go to the recommended levels, started having problems again. Should I add more liquid chlorine? View attachment 514227
Also, I have to say, I have never had issues this bad in the almost 30 years that I've been living here. This year has been the worst year in Minnesota for air quality warnings from the Canadian wildfires. Could there be a correlation for issues with the pool?
 
Stick with regular slam level until the water is crystal clear (throughout the whole pool) with no recurring dead stuff or live stuff. If your cya is 30 that’s 12ppm.
 
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Stick with regular slam level until the water is crystal clear (throughout the whole pool) with no recurring dead stuff or live stuff. If your cya is 30 that’s 12ppm.
Hello again, Pool is crystal clear. Yesterday I brushed the walls, stairs and floor of the pool several times throughout the day and had the Kreepy Krawly going for over 24 hours. Last time I brushed the floor, I didn't brush up any algae "dust". We have walk-in molded, fiberglass stairs... they have not been this white in maybe a year or so, they have looked stained. The yellow/brown substance is not settling as much on the top stair, however; I discovered more of a deposit in one of the skimmers yesterday and some this morning, it was gritty... like sand.

Test results: 7/17, 8:45 pm - FC 12.5 7/18, 7:37 am - FC 10.5 CYA 30.

With that overnight loss, do I keep with the SLAM or am I ready to do the mustard algae shock? Is it even mustard algae?

Thanks again for all your help!
 
Whether it is mustard algae or regular algae is unknown. Until you pass all 3 criteria you stick with regular slam level.
With that kind of overnight loss it seems it’s hiding somewhere. Do you have main drains? If so have you removed the covers?
Be sure when doing the oclt that it is dark for both tests. No UV exposure or that will skew the results in the opposite of your favor.
 
Whether it is mustard algae or regular algae is unknown. Until you pass all 3 criteria you stick with regular slam level.
With that kind of overnight loss it seems it’s hiding somewhere. Do you have main drains? If so have you removed the covers?
Be sure when doing the oclt that it is dark for both tests. No UV exposure or that will skew the results in the opposite of your favor.
Ok, Thank you for your response. The main drain is in the deep end... not sure how I would remove any covers? I'll continue on the SLAM course until passing the oclt.
 

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