I am so confused about mustard algae...

[Butterfly]

Well I did backwash which I will have to do again. And at this point, I might be on the verge of draining a lot to lower that CYA count.

Btw, I only see part 1, and I can't view part 2! :-(

Yes, backwashing is standard maintenance. The Deep Cleaning should be done maybe once a year, unless you have problems. Since this system is new to you, you would have no idea what might be happening inside the filter - or what previous owners might have had added.

Viewing part 2 works for me. Folks, ideas?

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That's interesting and makes it less likely to be yellow/mustard algae. You might get a skimmer sock to put over the skimmer and see if you collect anything that looks similar. If you do, then that's falling into the pool (could be pollen) and some is sinking to the floor and not getting circulated or caught in the filter. That would also be consistent with the fact that the SLAM didn't kill it.

Richard, I may be missing it, but I don't think OP did SLAM the pool. In the beginning when OP mentioned starting the SLAM, he thought his CYA was about 35, but has since confirmed 85 ish.

 

[Swampwoman]

Call me madcap, but having looked at the pictures, is there any chance its slight metal staining with a bit of normal particulate?

 

[chem geek]

Could it be bleached out green algae?

If there was algae in the water, such as it being cloudy or green and chlorine killing that algae, then yes it could have settled instead of getting properly circulated. However, in this case the appearance of this material looks like it is coming even when the water is clear and the chlorine levels are enough to prevent algae growth.

It seems more likely that something is getting into the pool and settling to the bottom (like pollen). Are there any trees or flowering plants near the pool? Again, I think a skimmer sock might help diagnose this and capture anything hitting the surface potentially before it gets waterlogged and sinks to the bottom.

Richard, I may be missing it, but I don't think OP did SLAM the pool. In the beginning when OP mentioned starting the SLAM, he thought his CYA was about 35, but has since confirmed 85 ish.

Thanks for catching that as I had missed that. Well, it's possible this is ordinary green algae if a proper SLAM wasn't done but this still seems odd. I agree with you that from the photos it doesn't look necessarily like algae and it's odd that it's so scattered about. Algae growth tends to start somewhere (sometimes multiple places) and spread out. This stuff looks more like stuff that just dropped to the bottom in various places.

 

[pisymbol]

Let me ask you all this, shouldn't my CC be >0 if it was MA during an overnight test?

TF-100 is on the way.

 

[Butterfly]

Let me ask you all this, shouldn't my CC be >0 if it was MA during an overnight test?

Not necessarily. That is why there are three criteria to determine when a SLAM is finished.

TF-100 is on the way.

Great!

 

[pisymbol]

Unfortunately, without the TF-100 I am partially in the dark. I did some numbers today with my 2005 and my overnight loss looked to be zero or very slight. I dumped 16oz of 73% carbonite to keep my FC around 10ppm since I see no algae growth right now (ph remains at 7.4 so no touch).

Could it be because its cooler now? The day I saw it, it was very hot and sunny.

I am now considering if this is more about pool circulation and particle filtration than about a biological nuisance.

Oh and guys, thanks for all the support!

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Call me madcap, but having looked at the pictures, is there any chance its slight metal staining with a bit of normal particulate?

Wouldn't that infer permanence of some kind? It brushes off with ease.

 

[Swampwoman]

Yes indeed. If it brushes off with ease, well then its "something." Got any goldenrod or mustard fields nearby?

 

[pisymbol]

Have tons of goldenrod in the general area (not necessarily in the field next to me but within a mile or two).

TFT-100 numbers are in (with speedstir!):

pH: 7.2
FC: 7
CC: 0 (note it remained 99% clear but got maybe a tinge of color to it, I assume it's near 0)
TA: 210
CYA: 70 (thank TFT-100, that was so easy)

I woke this morning and the spots are back.

Here is the other test, if I take the skimmer or brush and I excite the water over it (not touching the spots), the yellow stuff just explodes into the water and disappears. Is that typical MA? A friend suggested this test since he said that algae in general "sticks" and hat you literally have to brush it off not just generate a wave to get it off.

Could this be in fact SAND from my filter? The reason why I ask is that I see alot of it near the returns. And if I just wave over the particles they disperse quickly.

 

[chem geek]

Yellow/mustard algae does poof up like that -- it doesn't take much to disperse it and unlike green and black algae it doesn't usually stick tightly to pool surfaces. This type of algae does not like full sun so will tend to grow mostly or only on the shady side of the pool.

If it's sand, then it would need to be fine particles to poof like that, but having it be near the returns does sound like it may be something settling there. If the particles are too fine for your sand filter to capture, then you can Add DE to a Sand Filter to improve filtration capability.

 

[pisymbol]

Yellow/mustard algae does poof up like that -- it doesn't take much to disperse it and unlike green and black algae it doesn't usually stick tightly to pool surfaces. This type of algae does not like full sun so will tend to grow mostly or only on the shady side of the pool.

Well that's certainly not what's going on here with respect to sun. It is scattered all over the place (I have almost zero shade other than the deep side) and what's strange is it seems to always land in the same place (which I find really strange). I thought that could be related to circulation.

If it's sand, then it would need to be fine particles to poof like that, but having it be near the returns does sound like it may be something settling there. If the particles are too fine for your sand filter to capture, then you can Add DE to a Sand Filter to improve filtration capability.

It's the end of the season, arggh. I am going to test the pool tonight again (I zonked in 16oz of 73% to bring it up to 9+ past my target FC according to TFP charts) and then see what my overnight numbers are.

@chemgeek: How does MA grow? Does it grow SO FAST at these FC levels that the yellowish color will appear on the pool's floor everywhere in an 8 hour period? A colleague of mine said that it seems strange that this yellowish stuff appears this quickly AS he tends to believe that MA will first feel slimy on the floor and it takes some time to accumulate provided you have significant amount of FC.

 

[chem geek]

Yellow/mustard algae grows like other algae where it can double in population every 3-8 hours so no it won't appear everywhere in an 8-hour period, BUT if you brushed it or anything else up it of course could just settle back down again fairly quickly. Given everything you have written, it does sound like what you have is something fine that isn't getting caught in the filter and is settling into areas of the pool based on circulation patterns.

 

[pisymbol]

Yellow/mustard algae grows like other algae where it can double in population every 3-8 hours so no it won't appear everywhere in an 8-hour period, BUT if you brushed it or anything else up it of course could just settle back down again fairly quickly. Given everything you have written, it does sound like what you have is something fine that isn't getting caught in the filter and is settling into areas of the pool based on circulation patterns.

Richard, thanks a bunch for this dialogue. I wish I could buy you a refill on reagents or something as a token of my appreciation.

So with the TF-100 in hand and a SpeedStir in another I measured last night my numbers:

FC: 11
CC: <=1 (the water didn't return pink but it wasn't 100% clear either, like had a tinge of red in it, one drop of 871 brought it back to the clear)
pH: 7.2

This morning:

FC: 11
CC: 0
pH: 7.2

I'm gonna say that I don't have algae based on thei OCLT. I think what's happening is what you describe: I am brushing the pool vigorously and particles are then resettling to the bottom. I will do another OCLT and see if I get the same results.

 

[ping]

I would vacuum to waste as that will do two things for you, get rid of some of the particles that are sitting on the floor and lower the CYA level. This stuff might be bypassing the filter for some reason and vacuuming to waste might help.

If there is any color when testing for CC and one drop clears it up, count that as .5 ppm of CC. If you are using 25 ml of water, then each drop would count as .2 ppm of CC.

 

[pisymbol]

I would vacuum to waste as that will do two things for you, get rid of some of the particles that are sitting on the floor and lower the CYA level. This stuff might be bypassing the filter for some reason and vacuuming to waste might help.

If there is any color when testing for CC and one drop clears it up, count that as .5 ppm of CC. If you are using 25 ml of water, then each drop would count as .2 ppm of CC.

Thanks ping. That is what I'm attempting to do, vacuum a lot without actually brushing the bottom to displace the particles.

I'm not sure why my CC went from presumably 1 -> 0 over night but my FC count stayed at 11. Could be pilot error on my part.