Yellow Mustard Algae--this stuff will not die

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W

WCH

New member
Sep 10, 2023
4
Brewster MA
First post--this site has been very helpful.

New Salt water pool last year--had a few spots of yellow algae, did SLAM, followed instructions, all gone and done. Opened this year to a couple of spots again but otherwise clear water, raised the chlorine level to SLAM levels, it went away.

Well, it's back. Raised chlorine to SLAM for yellow mustard algae, it is laughing at me and proliferating. Water is otherwise crystal clear. I have raised the chlorine substantially, and it will not die. Have cleaned the filter, cleaned all items in the pool (robot, brush, net), brushing regularly. It re-grows literally in 2-3 hours. Should I capitulate to algaecide?

My numbers are as follows:

Ph--7.4
CYA--35
TA-45
Calcium Hardness--170
Chlorine--42.

Any help would be greatly appreciated. Thank you.
 
Welcome to TFP and thanks for searching through the site for help on specific items.
The SLAM Process is to raise FC to 40% of CYA level and for mustard algae to raise to 60% of CYA level after passing the criteria for the basic SLAM. I would suggest holding your FC at 24ppm (60% of 40 CYA) for minimum of 48 hrs.
Also, have you check for algae behind your lights (if they are removal) and in the weir door of your skimmer? These are common places where algae can lurk.
 
Welcome to TFP!

Could you describe the algae? What happens when you brush it? Is there anywhere specific that it seems to grow?

Just want to get a good handle on what you are dealing with so we can best help you get it gone.
 
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WCH said:
First post--this site has been very helpful.

New Salt water pool last year--had a few spots of yellow algae, did SLAM, followed instructions, all gone and done. Opened this year to a couple of spots again but otherwise clear water, raised the chlorine level to SLAM levels, it went away.

Well, it's back. Raised chlorine to SLAM for yellow mustard algae, it is laughing at me and proliferating. Water is otherwise crystal clear. I have raised the chlorine substantially, and it will not die. Have cleaned the filter, cleaned all items in the pool (robot, brush, net), brushing regularly. It re-grows literally in 2-3 hours. Should I capitulate to algaecide?

My numbers are as follows:

Ph--7.4
CYA--35
TA-45
Calcium Hardness--170
Chlorine--42.

Any help would be greatly appreciated. Thank you.
Click to expand...
A few thoughts:
- Algaecide only works before you have algae.
- Are you following the SLAM process? SLAM is not 42 FC.
- Your CYA is 40. There's no measurable amount between the 10's, so anything more than 30 is 40.
- Very high FC is a risk to pool and people. SLAM levels for CYA 40 is 16.
 
Answers--
1.The Algae is very pale yellow. It is proliferating on the bottom in patches. It disappears when brushed like dust.
2 Followed SLAM, zero progress at FC 28. Raised to over 40, am now making progress but it is not gone.

Hence my post--this stuff seems indestructible. I am on Cape Cod, water is crystal clear, am following the SLAM protocols. Testing is via Taylor test kit per recommendations here.
 
As I understood it, FC for Mustard Algae is 24 at CYA 40. Didn't touch it. And it's not dead algea accumulating--it grows back in patches exactly where it was before. I appreciate the responses, but something is definitely amiss. I got zero progress--and was going backwards--at recommended levels. I am gaining now at 40 FC level, so this is obviously very chlorine resistant algea or the charts are off. I am interested in your thoughts here, or has anybody else experienced this?
 
If you hang around long enough, you find that most new folks think they have some "super mega" algae or actual mustard algae (quite rare). What usually is the case is that they're new to testing, are not following SLAM properly, or are also adding magical potions from the pool store.

So - it's tricky for us to help. If you can share your pool logs, test regularly, fill out signature with pool type and equipment, and provide photos, we can be a lot more helpful.

Mustard Algae is a step in the SLAM process, but it's not THE SLAM process. How confident are you in your testing? Specifically CYA - if you were not making SLAM progress, and CYA is underreported, that can explain a lot.
 
Is the rest of your yard yellow with it pollen season in MA right now ?
 

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Completely confident in my testing. Taylor full kit, using it as directed. Have had the pool for 20 years, replaced last year with the SWG, it is 15 x 30 above ground, fully decked around, under oak and sassafras trees, so I get plenty of debris and pollen this time of year. I have a Betta running around which helps, but plenty still gets by for the robot to pick up. I think I understand the circulation patterns on the pool. And yes I am following the process exactly. You guys can keep telling me I don't see what I see, that's ok lol. I suspect that the particular species is very chlorine resistant since I had to raise the chlorine significantly to gain on it. I am now getting ahead of it, but I cannot be the only one who experienced this, and thought maybe somebody would have some insight into this odd problem. As I said in my first post, I had this stuff show up last summer, SLAMMED per instructons, it was cured promptly (3-4 days of the process) and did not return. I am sure it got a toehold over the winter as the FC dropped out, but this really has been something else.
 
WCH said:
under oak and sassafras trees, so I get plenty of debris and pollen this time of year.
Click to expand...
If the testing is good, and you're not losing FC overnight (Overnight Chlorine Loss Test), then you have enviornemtal debris.

It's indistinguishable from algae with the way it collects/pools.
 
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