Need Help with Stubborn Mustard Algae

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doc19

Member
Mar 18, 2022
17
Lewisville, NC
Pool Size
30000
Surface
Vinyl
Chlorine
Salt Water Generator
SWG Type
Jandy Truclear / Ei
Hi, all. I am battling a particularly stubborn mustard algae. I have followed all of the slam and mustard slam processes, including brushing the entire pool and all crevices 2-3 times per day. I am sanitizing tools and removed pool light, etc. My CYA is currently at 50, which is slightly high, but my FC is 57, well above the mustard range. I have been dealing with this for about 10 days and although it seems mostly cleared up, it is not going away. It is no longer creating lines/blobs on the bottom of the pool or creating clouds when I brush, but it is still settling in the seams of the liner and in the creases of the deep end.

20x40 rectangular salt water vinyl pool with 9 ft deep end and about 30,000 gallons.

I'm using tons of liquid chlorine and really need to get this under control. I would greatly appreciate any insights you can offer. Thanks!
 
doc19 said:
Hi, all. I am battling a particularly stubborn mustard algae. I have followed all of the slam and mustard slam processes, including brushing the entire pool and all crevices 2-3 times per day. I am sanitizing tools and removed pool light, etc. My CYA is currently at 50, which is slightly high, but my FC is 57, well above the mustard range. I have been dealing with this for about 10 days and although it seems mostly cleared up, it is not going away. It is no longer creating lines/blobs on the bottom of the pool or creating clouds when I brush, but it is still settling in the seams of the liner and in the creases of the deep end.

20x40 rectangular salt water vinyl pool with 9 ft deep end and about 30,000 gallons.

I'm using tons of liquid chlorine and really need to get this under control. I would greatly appreciate any insights you can offer. Thanks!
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You just need to follow the SLAM process. Having a FC of 57ppm is not following the process. Can you post the rest of your test results? A SLAM with active algae can often take a week or two.
 
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I’m sorry you’re going through this. How did you discover that you had mustard algae? What was your OCLT? I ask because sometimes people think they have mustard algae, but it’s maybe pollen or something else. That has happened to me.
 
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@Bperry - Hi, and thanks for your response. I have been following the entire process for 10 days. I did a regular SLAM following the directions in How to SLAM Your Pool. Once I completed that I raised FC to the higher mustard level. I have been at those levels for over a week and although the mustard algae is reducing, it is still not gone and I am well above the recommended FC level. However, when I have tried to keep it at the recommended levels, I get an increase in the algae. Here are all of my test results: FC 57, CC .5, pH 7.7 before SLAM, TA 60, CYA 40. I am in NC and the water temp is currently 51.

@kul - I wish it were pollen or sand getting into the pool, but it is definitely algae. It has all the trademarks and was very visible initially. It has gotten better, but has been quite stubborn.
 
doc19 said:
@Bperry - Hi, and thanks for your response. I have been following the entire process for 10 days. I did a regular SLAM following the directions in How to SLAM Your Pool. Once I completed that I raised FC to the higher mustard level. I have been at those levels for over a week and although the mustard algae is reducing, it is still not gone and I am well above the recommended FC level. However, when I have tried to keep it at the recommended levels, I get an increase in the algae. Here are all of my test results: FC 57, CC .5, pH 7.7 before SLAM, TA 60, CYA 40. I am in NC and the water temp is currently 51.

@kul - I wish it were pollen or sand getting into the pool, but it is definitely algae. It has all the trademarks and was very visible initially. It has gotten better, but has been quite stubborn.
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How are you testing the water? Something sounds fishy, no pun intended.
 
Donldson said:
Are you saying that you had this algae still visible when you discontinued the SLAM Process and started raising your FC?
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I finished the SLAM and passed the overnight SLAM test and did not see any visible algae. At that point, I raised my FC to mustard levels, the pool was completely clear, but within a day or two I could see small amounts again. Perhaps I had a false reading, but I had barely any CC throughout the whole SLAM, so it seemed accurate. I've now been at mustard level FC for about a week but I'm basically back to doing the regular SLAM process again with brusing and vacuuming because I can still see small amounts of mustard algae. At these levels, shouldn't the water have cleared by now? What am I missing?
 
doc19 said:
I finished the SLAM and passed the overnight SLAM test and did not see any visible algae. At that point, I raised my FC to mustard levels, the pool was completely clear, but within a day or two I could see small amounts again. Perhaps I had a false reading, but I had barely any CC throughout the whole SLAM, so it seemed accurate. I've now been at mustard level FC for about a week but I'm basically back to doing the regular SLAM process again with brusing and vacuuming because I can still see small amounts of mustard algae. At these levels, shouldn't the water have cleared by now? What am I missing?
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Something is very wrong. Your FC should only be at max of 30ppm even for mustard algae at a CYA of 50ppm. Where did you read a FC of 57ppm is needed? That’s not following the process and is risking a lot of damage and wasted chlorine.
 
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Bperry said:
Something is very wrong. Your FC should only be at max of 30ppm even for mustard algae at a CYA of 50ppm. Where did you read a FC of 57ppm is needed? That’s not following the process and is risking a lot of damage and wasted chlorine.
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I have a TF-100 Salt kit. For the 57 FC, I didn't intentionally get it that high, I accidentally overcompensated when adding liquid chlorine last night and am letting it drop back down. I am about to vacuum and backwash and will add fresh water which will help as well.
 
doc19 said:
I have a TF-100 Salt kit. For the 57 FC, I didn't intentionally get it that high, I accidentally overcompensated when adding liquid chlorine last night and am letting it drop back down. I am about to vacuum and backwash and will add fresh water which will help as well.
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OK, that’s good, but that’s nearly twice the maximum of what you should be at. I think I would be more comfortable, doublechecking your test process and making sure there’s not something wrong going on there. You’re using a 10 ml sample and not the 25 mL correct? You’re using one giant scoop of powder in that sample and it makes the water color turn pink correct? And you’re adding drops one at a time until the sample changes from pink to clear, correct? You then divide the number of drops in half to report your FC level.

ie, a FC of 57ppm would be 114 drops of the reagent.
 
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Honestly in water that is 50 degrees and an FC to CYA ratio well over 100% I'd be more concerned that a buildup of dust might be oxidized pieces of the liner or plumbing than algae.
 
Any construction going on nearby ? Any farm work being done getting ready for your NC spring to arrive real soon ?
 
Bperry said:
OK, that’s good, but that’s nearly The maximum of what you should be at. I think I would be more comfortable, doublechecking your test process and making sure there’s not something wrong going on there. You’re using a 10 ml sample and not the 25 mL correct? You’re using one giant scoop of powder in that sample and it makes the water color turn pink correct? And you’re adding drops one at a time until the sample changes from pink to clear, correct? You then divide the number of drops in half to report your FC level.

ie, a FC of 57ppm would be 114 drops of the reagent.
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yes, that is what I'm doing. Will report back new numbers once I'm finished replacing water after vacuuming and backwashing.
 
Donldson said:
Honestly in water that is 50 degrees and an FC to CYA ratio well over 100% I'd be more concerned that a buildup of dust might be oxidized pieces of the liner or plumbing than algae.
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Interesting thought. I will definitely keep an eye on this, but given that it is still behaving exactly like mustard algae, I am leaning toward it being very stubborn rather than dust/damage.
 
Newdude said:
Any construction going on nearby ? Any farm work being done getting ready for your NC spring to arrive real soon ?
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None of this, but farm work will likely start soon. I think I'm still in the clear on this, but maybe only for another month or so. We've had a very cold winter (for us) with snow predicted again for next week so that may slow things down a bit.
 
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