Mustard Algae???

[Jaybird70]

I'm a first year pool owner, who just went through the process of converting from baquacil to chlorine. Things have been going great until recently some brown stuff started showing up on the bottom of the pool. I thought it was just dirt, vacuumed up, but then kept returning.

(I'll admit I got a little lax with the bleach )

And then, about 2 weeks ago I walked out and had spots of it all over the bottom of my pool and a thin layer of yellowish colored film. I'm assuming this is mustard algae. I shocked the pool to 15 and have been putting it up to 15 every night before bed and brushing every night for the last week.

Finally I decided to try some 60% poly. Nothing I've done has worked thus far. I just finished brushing, redosing and testing the pool again.

Above Ground Pool 12,000 gallons

TC = 15
FC = 15
PH = 7.5
CA = 180
CYA = 30
TA = 130

If someone could walk me through what I need to do I'd be really greatful. This is my first time dealing with algae.

[Ohm_Boy]

If those numbers are right, you may need no more than a finer filter - like a handful of DE in the skimmer.
Your numbers are pretty much textbook spot-on, and you are evidently able to maintain 15 on chlorine, so I'm thinking that you do not have a problem with anything that is using up chlorine. You are at the proper shock level according to the 'best guess' chart. So, unless the polyquat is doing something odd with the chlorine, it doesn't seem to me that you are needing to kill anything in your pool.

That leaves me thinking that your 'dust' is simply brushing into suspension, passing through the filter, then settling back whence it came.

I'll be seriously curious to hear more learned opinions than mine on this one.

[Poconos]

Jaybird,
You didn't mention what kind of filter you have. The DE trick only works with a sand filter. If you do have one then it most likely is not filtering the fine stuff which could be pollen, dust, dead algae. As for the DE, the trick is to add enough to raise the pressure about 1 psi. The amount you add depends on the size of the filter and other factors. Start with 1/3-1/2 cup, mix in a pail of water, add to the skimmer, wait 20 minutes and see what the pressure rise is. Repeat as necessary. Once you're 'calibrated' you just add that much at once. You have to add any time you backwash because the DE is washed out.
Al

[fuelman]

Read through this: http://www.poolforum.com/pf2/showthread.php?t=5423
I had this "hard to kill" algae. I shocked to 25PPM with a CYA of 50PPM and held it there for about 3 days brushing the pool daily and running the filter 24/7 and got rid of it!!

[Jaybird70]

I have a sand filter. I'm pretty sure it's algae, as it feels slimey and when I backwash the filter the water is somewhat green. Also it I let if go, it just grows and grows. So, maybe I just need to bring my chlorine up higher, I haven't gotten it past 15 ppm so maybe it's just really hard to kill.

I'll have to wait until after this weekend as we're having heavy rains that are suppose to last all weekend. I'm sure my pool will be a pretty sight after that. Sigh.

BTW Feulman, that stuff in your pool looks almost exactly like mine, except I have a yellow film everywhere. The pool is clear until I start brushing and then it gets cloudy. I'll definately try shocking to 25 once the rain stops.

[chem geek]

Users of this forum have found that it takes a lot more chlorine to kill the mustard/yellow algae than it does for the more common green algae. This chart shows the amount of Free Chlorine (FC) needed to achieve the desired level of disinfecting chlorine (HOCl at the top of each column) at various levels of CYA. To kill mustard/yellow algae, it takes about 1.0 ppm disinfecting chlorine so that would be at least 21 ppm FC with your 30 ppm CYA (more common green algae only needs no more than 0.3 ppm disinfecting chlorine). The advise of using 25 ppm FC is good. In addition, I would lower your pH to at least 7.2 (but not lower than 7.0) before adding the chlorine since the chlorine will raise the pH and make the chlorine less effective.

Then, it's patience, patience, patience.

Richard

[Jaybird70]

I'm back.

Long story short, I shocked to 25 for several days and brushed every night and I believe I have only succeeded in bleaching my liner. Is this going to cause huge problems?? Guess I must have keep it too high too long or maybe the hot Texas sun assisted.

Anyways, after about a week I gave up and immediately the mustard algae returned. I just didn't have the heart to fight it the last week with Halloween and some personal things that came up.

So any suggestions would be great, I'd like to start closing, but I know that I can't until I get this solved. Also, if someone could let me know if I've really harmed the liner by bleaching it.

Also, my PH has gone up a bit, so I'm going to get some decreaser to take care of that. Numbers are below.

CYA 25
FC 4
Forgot to test TC
PH about 7.6, not 7.5 but not quite 7.8
TA 125
Ca 180

Thanks in Advance for everyone's previous help and the help to come.