Mustard Alge problem - please help

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ummhasan

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Jun 28, 2012
92
Michigan
Hello again all,

So my pool was great until my SWG stopped working and we developed a mustard alge problem because I was not taking care of the water (boo for me)!

Since, my husband fixed the SWG and I keep doing the same thing over and over almost every week - shock with a 2.75 no phosphorus bleach, vacuum like crazy until it's all clear, raise the run hours of the SWG and Pump until things seem all clear. BUT, lo and behold, the kids don't swim for a few days and here comes the algae again!

I've forgotten how to use the FAD-DPD to test FC and I'm sure not doing this has contributed to my problems - but - I'm trying to get back on top of things before summer ends.

So, here's what I know right now:

CC Over 10 maybe - Very dark yellow but not orange - SWG running 9 hrs
PH above 8.2 - a dark hot pink (I added 16oz of muriatic acid 31.45% 20 baume' last week and yesterday and it's still high)
Salt strip reads 6.6 so according to the directions it's at 6250 (no high salt warning from the SWG and in fact had low salt warning two wks ago so added 1 bag)
CYA about 28 - just under the 30 mark - tops off the cylinder
TA - 120

I think it's in my signature but just in case it's not, I have an Intex Metal Frame 18 x 48 pool with an Intex large sand filter and intex 8110 SWG

I read how to SLAM it and plan on doing that 1st but I need to know how to test my FC again - I searched it but didn't find an exact answer.

I almost forgot - the water is very clear! Only the algae is there, clearly seen at the bottom and all around the bottom edge of the pool and IS more prominent in the shaded areas.

Thanks for your time
 
ummhasan said:
...we developed a mustard alge problem
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Are you sure it's mustard algae? Can you post a pic? Is what you're seeing gritty or slimy?

ummhasan said:
I've forgotten how to use the FAD-DPD to test FC...I need to know how to test my FC again...
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Here are the Extended Test Kit Directions. Scroll down to the FAS-DPD Chlorine Test section.

ummhasan said:
CC Over 10 maybe
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I think (and hope :!: ) you mean FC is 10, not CC.

ummhasan said:
PH above 8.2
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You want to get this down to 7.2 - 7.5 before you begin the SLAM Process. Once you begin SLAMming, do not test pH until FC drops below 10 ppm. I would also turn off your SWG once you begin SLAMming and use plain unscented liquid bleach exclusively as your chlorine source. When done SLAMming, you can turn SWG back on.
 
I think (and hope :!: ) you mean FC is 10, not CC.
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Well, I'm referring to the OTO test.

You want to get this down to 7.2 - 7.5 before you begin the SLAM Process. Once you begin SLAMming, do not test pH until FC drops below 10 ppm. I would also turn off your SWG once you begin SLAMming and use plain unscented liquid bleach exclusively as your chlorine source. When done SLAMming, you can turn SWG back on.
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Today, I added 16oz more of muriatic acid and vacuumed again. I've turned the SWG off now. Is the 2.75 no phosphorus bleach good enough? Do I need to double the amount?

I'm adding some photos I took while vacuuming today. Keep in mind that I also vacuumed yesterday and it was MUCH worse. After I was done, the pool looked clear like the side that I already vacuumed and this morning, the bottom was covered again as the side that I had not yet vacuumed. Today, I went over the whole pool twice including the bottom part of the walls. It is NOT slimy looking or gritty looking. As I vacuum, it seems powdery. It actually looks more like rust than mustard.
 
ummhasan said:
can someone please advise me. Thank you
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Follow the link Bo gave for Extended Test Kit Directions and give us the test results, especially the FC and CC.

You should use plain unscented bleach/liquid chlorine. Most bleach now is 8.25% and is what most folks use for normal dosing and for SLAMing if needed. Some favs are Walmart Great Value, and of course Clorox. Both are 8.25%.

So, get the pH down to about 7.2ish and start the SLAM process. Your SLAM shock level with 30 CYA is about 12. Use the PoolCalculator to help figure the doses.

Post back if you have questions, someone will be around and be glad to help.
 
I tried to post from my mobile but it seems it didn't post - there may end up being a duplicate post.

Anyway, I did the FAS-DPD and retested the OTO and PH here are the results:

FC: 4.5
CC: either .5 or 1 (turned back pink after a few seconds after the 1st drop)
TC(oto): between 5-10
PH: maybe 8

Also, I had forgotten to turn my filter off after back-washing, which I always do after vacuuming this stuff out, so, it's been on for 24 hrs. The SWG's been off since yesterday morning and I hadn't shocked yet (waiting on some guidance first). So, there's been no chlorine additions as of my 1st test post.

I'm attaching a pic of the pool floor and the Ph/OTO test. I did flip the photo of the test but for some reason it keeps flipping back when I post it.

Also, what do you all think of the first set of photos? Does this look like mustard algae?

Thanks
 
ummhasan said:
Keep in mind that I also vacuumed yesterday and it was MUCH worse. After I was done, the pool looked clear like the side that I already vacuumed and this morning, the bottom was covered again as the side that I had not yet vacuumed.
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This statement combined with your most recent set of photos (which are a big help in diagnosing, BTW) point towards mustard algae, especially the clump-like growths on your most recent photos.

Time to begin The SLAM Process. Since your FC is at 4.5 (per the more accurate FAS-DPD test), lower your pH to around 7.2 before beginning the SLAM process . Once you begin the SLAM process, do not test pH until you are dome SLAMming. The high FC of the SLAM process invalidates the pH test. Once you have completed SLAMing your pool in the standard way, raise the FC level up to the extra high mustard algae shock level for 24 hours. Use the Pool Calculator or see the Yel/MstrdShock column in the chart in this post to find your mustard algae shock level. Make sure you have plenty of plain unscented bleach on hand.

For more information on Mustard Algae, see this article: Mustard Algae
 
Just out of curiousity when you say... "TC(oto): between 5-10" ...are you by any chance getting that from the "5 10" printed on the comparator? IF so, then you should know that the "10" printed there is for the Bromine reading at that level and has nothing to do with the Chlorine reading. My apologies if you already are aware of this. Thought I'd ask, just in case. :)
 

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Ok, so today is day 3 of SLAMming the pool and it looks pretty good! (pictures below).

I just have a couple questions. During the whole SLAM process, it seems that my CC was zero. No matter how many drops of R003 that I added, the water remained clear - that means zero right? and is this a problem? Did I do something wrong? The SLAM post says to SLAM until the CC is at or below .5. Mine was never above that but I kept SLAMming because the algae was still there. Today, there was only a few bunches of the mustard algae on the pool floor. FC was at 17 this morning and I need it to be a 18.5 for Mustard Algae shock levels with CYA of 30. So, I added some more bleach to bring it back up, vacuumed the whole pool again, back-washed again, and the pool looks GREAT!

So, a few things to point out:

1 - It IS getting better each day and today was only very little alae
2 - When I backwash, I always put my garden hose inside the skimmer to backwash with clean clear water, not lose salt or CYA.
3 - When I add bleach, I also pour some into my skimmer to make sure I get a good amount into the sand filter to kill any algae in there.
3 - Today, the backwash water was perfectly clear! The last two days it was very light brownish/greenish when I back-washed.
4 - I'm not totally sure if my CYA is really considered 30. When I test it, I can still slightly see the black dot until I totally top off the cylinder. When I put the final drop before overflow, then I cannot see the dot at all. Is my CYA really between 25 and 30?
5 - If when I go out tomorrow morning to check things out, I see no algae, does that mean I'm done? If so, and the FC comes down to normal levels by tomorrow night, will it be safe to swim on Saturday?

Thanks
 
4. Pretty close. I would use 25 as a guideline for CYA

5. You have finished the SLAM process when.....

1. Your pool water is sparkling
2. Your CC's are .5 ppm or less
3. You can hold your FC overnight without losing more than 1 ppm.
 
ummhasan said:
1 - It IS getting better each day and today was only very little alae
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:goodjob:
ummhasan said:
2 - When I backwash, I always put my garden hose inside the skimmer to backwash with clean clear water, not lose salt or CYA.
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No harm in doing this, but some pool water will still get through.
ummhasan said:
3 - When I add bleach, I also pour some into my skimmer to make sure I get a good amount into the sand filter to kill any algae in there.
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Would not recommend doing this unless you dilute the bleach with water. Undiluted bleach (or any other chlorine source for that matter) that is routinely poured into the skimmer results in a concentration of very highly chlorinated water that may cause your pump seals to fail prematurely if this practice is done over a longer period of time. The elevated chlorine from the SLAM process will kill any algae in the filter.
ummhasan said:
3 - Today, the backwash water was perfectly clear! The last two days it was very light brownish/greenish when I back-washed.
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You are definitely making good progress!
 
Great! Thanks to both of you! So just now, I had tested the FC and it was at 15.5 after the hot sunny day today after my morning addition. I added the amount calculated on the pool calculator to maintain SLAM FC overnight. If I test in the late morning and find it still holding at or above 17.5 I should be done. Then I can just allow the levels to drop naturally and swim when their safe - right?

As for the breech in the skimmer, I only did this during the SLAM, otherwise I only use my SWG. I'll remember not to do this again next time if there ever is one (hopefully not)! This brings me to the question - when is it safe to turn the SWG back on?

Thanks so much for your help and time!
 
Sadly, I didn't see this until this morning and didn't recheck. I woke up late today so didn't get out there to check things out until 11am. At that time, FC was down to 14 (lower than ever since I've been SLAMing. There was also still some - very few, maybe 5, clumps of algae on the bottom. So I guess today is not the day.

I vacuumed the whole pool again and added a whole 96 oz jug of 6% bleach to sustain today's Sun light and hopefully maintain shock level throughout the day. I'll check FC again tonight, add if needed, test after an hour as suggested, then see if I pass the overnight FC test and have no algae tomorrow.

So, I have company coming tommorrow expecting to swim - sadly! So let's say, if I do poss the FC test tonight and have zero traces of algae tomorrow, and I add additional water (my water is low anyway) and some stabilizer (due the added water) to bring down the chlorine levels, would it be safe to let them swim if FC is back down to about 9 by the time they come? Or would this just be a very bad idea?
 
You can swim even if you havent passed the overnight test. Swimming in a pool with algae is no different than swimming in a pond. Just make sure you can see the bottom. For safety reasons, you have to be able to see a swimmer on the bottom. Just let your FC dip below shock level - it's safe to swim up to shock pevel for your CYA level. After the party, bring the FC back above shock level and continue the SLAM.

Edit: my apologies for the worst grammar ever.
 

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