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.

[chem geek]

I'm sorry your liner got bleached. Others who used the same high chlorine levels didn't get their liner bleached though they said that the sun will bleach it. Others with vinyl pools can tell you more about whether bleaching makes any difference. Typically, it's acidic conditions that are the problem with vinyl in terms of weakening it. Bleaching (which with chlorine is alkaline, not acidic) is just a color fading and doesn't represent any loss of integrity of the material itself. Did the liner just get bleached where you poured in the chlorine or is it bleached everywhere or just where the sun hits it, etc.?

Since your algae came back, you can try using PolyQuat algicide after you get rid of the algae (again -- using chlorine -- if your CYA is really 25, then you can use 20 ppm FC instead of 25 that you did before). I assume you cleaned out your filter after the algae was gone so as not to reintroduce it back into your pool. After killing the algae with chlorine, adding PolyQuat can help prevent it from coming back (you said it didn't work, but PolyQuat is better at prevention than killing an existing algae bloom and I'm not sure what you meant by "it didn't work"). Another option for you for preventative maintenance would be to use borates (50 ppm Boron from Borax), but that's a one-time decision to make. Evan and others now have Borate pools and are happy with it (see this thread for more info), but this is still preliminary and we don't know yet if such high borate pools would prevent this particular algae you are getting or not.

If you wanted to, you could experiment by taking two large buckets of your pool water that has this algae in it and try adding a very small amount of Borax to one of the buckets -- proportional to 50 ppm. It only takes 0.5 (that's one-half) of an ounce weight of Borax for 10 gallons to get 50 ppm. If the bucket with Borax (and maintained normal chlorine levels) kills and prevents the algae from growing while the bucket without Borax has the algae thrive, then you've got a plan. You can also use this technique to test out the PolyQuat as well (using another bucket or doing the experiment separately after washing out the bucket used for the Borates test) though you mentioned you had tried PolyQuat and it didn't work, but try killing the algae in the bucket with chlorine first and then see if PolyQuat prevents it from coming back.

Unfortunately, you didn't get the same positive results that others have seen in battling this algae -- you did get rid of it (visibly), but it came back. Carl and others may have some other suggestions that are of a "last resort" variety including testing for phosphates that is normally not done unless everything else does not work.

I also wonder if there is any remnant from previously being a Baquacil pool that could be causing an issue here. Perhaps others may know.

Richard

[Jaybird70]

Thanks so much for the info.

My whole pool is in direct sunlight almost all day, not even any trees for shade, I suspect that may have caused the problem as one area of the pool, by the ladder has less sunlight and the liner is less bleached there.

I didn't realize poly quat was primarily for maintenance, so that would clarify why it did not clear up the algae bloom.

I'm going to try shocking to 20 again and keeping a closer eye, I was only bringing it up to 25 once a day at night, so maybe that's why it didn't clear up all the way, plus I suspect I didn't get the algae completely off the ladder, another reason it may have returned. We're taking the ladder out as well to see if this helps.

Thanks again.

[chem geek]

I didn't realize poly quat was primarily for maintenance, so that would clarify why it did not clear up the algae bloom.

I'm going to try shocking to 20 again and keeping a closer eye, I was only bringing it up to 25 once a day at night, so maybe that's why it didn't clear up all the way, plus I suspect I didn't get the algae completely off the ladder, another reason it may have returned. We're taking the ladder out as well to see if this helps.

Yes, the PolyQuat in the presence of lots of algae will generally be overwhelmed (i.e. get used up) which is why it's much better as a maintenance item while chlorine is the true algae killer when you've got a lot of it. Also, high chlorine levels will get consumed by PolyQuat and the PolyQuat will get converted into another form (essentially broken into pieces and not so "poly") that is still somewhat effective so bottom line, use PolyQuat at the END of a chlorine shock session after the chlorine levels have dropped to "normal" and for maintenance.

Yes, if you only had your FC at 25 at night, then it is quite likely that the FC dropped by as much as half by the end of the day due to sunlight. That would allow the algae to regroup, so to speak. You've got to maintain the minimum of 20 ppm FC throughout the day so if you start with 25 ppm at night, check it in the morning, add chlorine as needed, and again later in the day, if possible. If you are away at work, then test and add more chlorine as soon as you get home. If there was any way for you to even partially shade your pool to prevent chlorine loss from sunlight, then that would be good (even putting in floaters or other opaque objects would be helpful).

Also, keep your pump running continuously during this process to ensure good circulation.

I'm crossing my fingers that the main problem is that you just didn't keep the FC up high enough consistently, but you'll still have to have some sort of algicide maintenance to do after you've killed the algae and we haven't really figured out what will keep this stuff at bay (yet).

Richard