Mustard algae with 5 ppm fc?

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mxfan

mxfan

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LifeTime Supporter
Jul 24, 2008
68
Shingle Springs, CA
I have had a problem with my pool basically since it was built 5 years ago. The problem is the pool looked great all winter, I keep the filter running and all chemical levels at TFP recommended levels (greatly appreciate this site) throughout the winter, and I pay especially close attention to the FC levels (I have had black algae in the past and i don't ever want it again).
I kept the fc levels between 5-7 ppm to avoid any algae issues this last winter.
I actually had our pool completely re-done last a year ago because I could not figure out what the powdery/dust was coming from, and I thought it was actually the finish of the sculpted rock style finish coming off?
Well the first time in the pool and the same issue has come back. The pool itself looked great, clear and sparkly. Once it gets stirred up it turns cloudy. If I brush the walls it goes from crystal clear to green and I can no longer see the drains at the bottom of he pool (it's only 7 feet deep).
I am planning on doing an overnight fc test tonight, so just looking for ideas?
2 years ago I tried to look at the particles under a microscope, but i was not able to determine if it was plant like due to the low quality microscope that I have.
Is it possible to have mustard algae if the fc was always maintained (I'm very aware of fc levels) 5-7 ppm?
Here are my current levels

Fc 4
Cc 4
Ph 7.6
Ta 75
Ch 260
Cya 60
Temp. 80

Thank you! Sorry for the long post...very frustrated.
 
It could be mustard algae, or dust, or pollen. Mustard algae tends to grow on the walls and floors on the shaded side of the pool, and will go away when you are at shock level, only to come back when FC returns to normal levels. Dust and pollen tend to accumulate on the floor but not the walls and continues to accumulate even when you are at shock levels.

Hopefully your CC level isn't actually 4?

With CYA at 60 you want to keep FC at 5 or higher at all times.
 
Jason,
Thanks for the quick response! My goof, the cc is 0, i meant tc.
When I brush the walls is when I get the issue, I get the same amount (approx.) whether the walls are in the shade or in direct sunlight. We do have a lot of pollen, but from reading this board the pollen seems to only be on the floor, and not necessarily on the walls?
I brushed the walls and put a sample of the 'dust' into a mason jar so I could see what it looked like (after it settled). It was cloudy at first, than after about 12 hours it settled to the bottom of the jar.
I have included a few photos of the pool, and the sediment in the jar, in hopes that it helps determine the issue.
Thanks again!
...Eric
I normally run the cya level closer to 90, but we have been having a unusually cold a rainy climate and not that much sun so I wasn't too concerned with the cya. I am going to raise it back up to SWG recommended levels for sure.



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Overnight fc test-
Lost 1.0
Started at 3.5 fc last night and it was 2.5 this a.m.
I am adding liquid chlorine to get it back up to at least 5 ppm, but according to the test it is not mustard algae?
The pool is almost back to clear this morning, which is normal for it to take about 2 days to clear after I brush it and stir up all the 'dust'.
Any ideas?
Since I had the pool re-finished last year by a different pool builder, I am puzzled as to what the 'dust' is? Is there anyplace to send a sample for testing?
Thank you!
...Eric
 
Since you lost 1ppm and the water is not clear, I wouldn't call that a pass, especially since FC is on the very very low end, for your CYA level. FC of 3.5 is too low with CYA at 60. Your target FC is 6-7 with 4-5ppm being the minimum, especially if you live in an area that is prone to MA.

It would not hurt taking the pool up to shock level at this point and then trying the OFCLT.

Good luck :goodjob:
 
Thank you for the replies!
I run the filter from 9:00 am to 5:00 pm. The pool is clear this morning, and I added some liquid chlorine to bump it up to about 6 ppm. I have turned up my SWG to 50% (it was at 30%), and also added in some Stabilizer to get the cya back up to 80.

Jason-I have the jar with the 'dust' in it, and I can dump out the water and let the dust dry to try the muriatic acid test.

I will keep brushing, vacuuming and filtering, and see where it goes.

Thanks again for all the input!
...Eric
 

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duraleigh,
I brushed the pool Saturday late afternoon, and the pictures were taken Sunday a.m.
I didn't run the filter after I brushed on Saturday...thinking that maybe the dust would settle overnight and I could just vacuum it up. Didn't work (as you can see from the pics) :(
I ran the filter all day Sunday and all night last night so I could do the overnight fc test.
I didn't have time to take any pics this morning, but the pool is back to clear.
Thanks.
...Eric
 
dmanb2b said:
Since you lost 1ppm and the water is not clear, I wouldn't call that a pass, especially since FC is on the very very low end, for your CYA level. FC of 3.5 is too low with CYA at 60. Your target FC is 6-7 with 4-5ppm being the minimum:
Click to expand...

why does his FC level need to be 6-7 with a CYA level of 60? Pool School states that FC should be maintained at 3-5 with CYA between 60-80. Confused :?
 
mx702 said:
dmanb2b said:
Since you lost 1ppm and the water is not clear, I wouldn't call that a pass, especially since FC is on the very very low end, for your CYA level. FC of 3.5 is too low with CYA at 60. Your target FC is 6-7 with 4-5ppm being the minimum:
Click to expand...

why does his FC level need to be 6-7 with a CYA level of 60? Pool School states that FC should be maintained at 3-5 with CYA between 60-80. Confused :?
Click to expand...

Maintaining a SW pool at non-swg levels is not an issue, especially when the water is cloudy or just not "polished". I did however miss that this was a SWG chlorinated pool. :oops:

The SWG FC/CYA traget levels were determined to be acceptable as chlorination is very consistent (vs. manual dosing) and there is some theory that your water is shocked as it passes through the SWG cell each day. That said, the FC/CYA chart is a suggested guideline that likely works 95+% of the time. To the extent you live in an area where MA break outs occur often, water just does not sparkle, etc., elevating FC by 1-2ppm and raising your target FC to non-SWG levels won't harm things a bit, especially with CYA at 60. :goodjob:
 
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