long term mustard algae problem and no FC

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martypres

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LifeTime Supporter
Sep 15, 2010
17
Central Maryland
My pool has had a persistent mustard algae infestation for over a year. I've tried many treatments, including Yellow Out, Yellow Treat, phosphate remover, and shocking to no avail. I was even hopeful that it might die off over the winter under an opaque cover, but no luck there. Every time I used a 'Yellow' treatment it would make it go away for a few days only to return again. I even tried multiple concurrent treatments to try to finish it off. Eventually, I gave up trying to eradicate it and I would brush and vacuum frequently to keep it from getting out of control. I have not had a steady FC level in a long time.

So far this year I have done one yellow treatment, and 3 rounds of phosphate remover to get that level down. I even took a sample in last week for a chlorine demand test. They recommended 37 lbs of Burn Out 3 shock. I did not follow that advice because I was afraid the resultant 73 FC level could cause problems. But I have heavily shocked the last 3 evenings. From reading posts on this forum I recently purchased a TFT-100 test kit and it arrived yesterday. The first evening I put in 20 182-oz.bottles of bleach. The second evening I did the same. Both times the FC was back to zero by late afternoon. Last night I put in 6 bottles (running out of bleach) and its back down to zero FC now. I have also been brushing or vacuuming daily. I'm looking for advice on how to proceed - how much to shock and how often. Plus any other advice for a semi-desperate pool owner who thinks the light at the end of the tunnel is most likely an oncoming train.

Here are my vitals:
FC 0
CC 0.5
CYA 50
TA 130
pH 7.5
CH 220
 
I have not had a steady FC level in a long time.
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....and therein lies the problem.

Regardless of how much it takes it is absolutely mandatory that you continue to add chlorine until the chlorine oxidizes the organics that are in your pool. If I remember, all the "yellow" stuff you've been using is a huge consumer of chlorine as is the mustard algae.

Please read the "ABC's of Pool Water Chemistry" up in Pool School and it will help you understand what you need to do.

Simply put, however, you have not used enough chlorine.

Follow the guidelines and suggestions in pool school and the mustard algae will go away.
 
Only thing I have to add is to make sure you are not reintroducing this yellow plague back into your pool from things like pool noodles...........i.e............spongey breeding factories if they are infected.
 
Thanks for the tips. I do realize the importance of FC and hope to have it restored to my pool ASAP. I have read the Pool School and have a few follow up questions about shocking. If I have understood the articles the key is to keep the pool continually at shock level until all the CC is gone. What level should I be shocking at - regular shock (15) or mustard algae shock (24) or higher? I got those numbers from the Pool Calculator. It seems like no matter how much I put in it comes back down quickly. I will have to shock with 73% cal-hypo until I can pick up more bleach. I have been clearing out all the local Target, Walmart, and Costco stores of bleach lately - 48 large bottles so far. Unfortunately, I did not have the test kit when I started this process to see what my original CC levels were, and verify that I am making progress.
 
With a CYA of 50ppm, the shock value you should be trying to hold is 20+ ppm of FC.

Don't worry, you are making progress....that's why your FC is going away so fast. It consumes the organics but, in so doing, it consumes itself as well.
 
Just shocked with my last 2 bottles of bleach and 9 lbs of 73% cal-hypo, which should get me to FC 29 in theory. Will check levels in a couple hours, and then again in the morning, and add more shock as needed. Plan to pick up more bleach tomorrow. Its always fun to hear the cashier's comments when you check out with 20-30 bottles of bleach. A few of my favorites: your house must be pretty dirty, plan on doing some pressure washing?, cleaning up a crime scene? :lol:
 
The shock level for getting rid of yellow/mustard algae for good is an FC that is around 60% of the CYA level. You not only need to put into the pool everything that has touched the water like poles, nets, brushes, etc., but you also need to get behind light niches and under any removable ladders. Remember that this type of algae prefers shade and will hang out in such areas especially if there is little chlorine circulation. You'll also want to make sure to wash your swimsuits using soap and water.
 
I threw in everything that has touched the pool (vacuums, brushes, nets, toys, floats), and will wash all the bathing suits and towels. I continue to brush daily including around lights, skimmer, ports, and returns.

That may be premature though as I still have not been able to maintain my FC level through the night. I get it up to shock level (29+) in the evening, and check my levels around midnight (still good). By morning I have lost FC - this morning it was down 3. Then throughout the day the FC goes all the way down to 0 by the time I get home. It doesn't seem to matter if my FC level is 16 or 29 or 53 it all goes away during the day. At that point my CC consistently measures 0.5. Is it normal to lose that much FC during the day when my CYA is 50? Why the huge difference in FC loss overnight versus during the day?

I also have a question about the FAS-DPD test. When dealing with higher levels of FC I have trouble knowing when to stop. When I get near the anticipated level the sample turns a very light shade of pink but never seems to be totally clear. One time I added an extra 20 drops above where the level should have been but it never went clear. Because of that I also have trouble determining the CC level when FC is high.
 
I just found the 'Extended Test Kit Directions' post under 'Testing & Balancing Water' so I answered my own question about the FAS-DPD test. The sample needs to turn completely clear instead of light pink. Not sure why mine did not when FC was high. Perhaps I need to use more R-0870 powder in the future.
 

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Martypres, sorry late into your thread.

I had the same problem as you..until i found this site I was spending $600.00 for 3 months of Chlorine. Yellow algae is bad stuff.

I have to put in at least 30 gallons of 12.5 Hypo cal to get to a point of keeping minimal FC, as the experts here say, keep at it, it is a process and not a quick overnight fix.

Also I see you have a DE Filter, if its a Hayward like I have , when you open and close did you take apart the top and Put the Fingers type filter in a Muratic acid bath? This cleans the filter great and mine had algae on them and provides a fresh start. I also change the DE earth 3 times during this process as well and I think it helped me.
 
Also while you are at it cleaning out the inventories of your local stores bleach, start shopping for 20 mule Borax now, use the pool Calc to determine your quanity. This made my water sparkle, soften it up and helps in my algae prevention plan.
 
Its always good to hear from others who have dealt with the mustard algae plague ... and prevailed. I first encountered this menace during the late summer of 2009. It wasn't until the next season, 2010, that I realized how bad it was, and nothing I tried last year worked (as noted in an earlier post). Most pool owners who have not experienced the yellow algae don't understand how nasty it can be, and how hard it is to get rid of.

That being said I am hopeful that this intensive shocking regime is doing the trick. I finally was able to hold FC steady around 34 overnight! Yesterday evening the FC had NOT dropped to zero as it had the past four days so I knew things were getting better. Depending on this evening's CC reading I may need one more night of shocking but could be almost finished.

Grand total of chlorine used for shock thus far:
103.2 gallons of 6% bleach +
11 lbs of 73% cal-hypo =
equivalent of FC 222
 
Make sure you Brush the sides and Bottom Nightly as well.

Stay the course and I know you will be happy in the end, albeit a little lighter in the wallet with the chlorine cost.

Also I use the 12.5% Chlorine liquid from my pool store, they have a Bottle deposit program, so I pay less for the cost of Chlorine by the gallon and its more convenient than the 6% from the stores. (bonus is no recycle waste)
 
I have been brushing daily, vacuuming, and backwashing as needed.

The latest update is that I have maintained FC the last two nights, and the CC appears to be down around 0.5. Last night FC 33, CC 1 and this morning FC 33, CC 0.5. Yesterday the FC dropped from 34 to 3 during the day. Today the drop was 33 to 14. Am I done or should I continue to shock at mustard algae level (FC 29+) overnight?
 
You need to be able to maintain a FC of 3-5 ( depending on your CYA and or if you have a SPA attached) you will have normal overnight drop.

Does the pool look clean?

It took me 2 weeks to get the thing under control with Heavy Liquid Chlorine Shocking, to finally maintain FC of 5 with littel overnight loss. I am up north so your weather is warmer and sunnier than me.

I also did the Borax treatment and couldnt be happier with the results.
 
Am I done or should I continue to shock at mustard algae level (FC 29+) overnight?
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You are finished when you meet these criteria....
1. Your water is crystal clear.
2. You lose less than 1.0 FC during the FC overnight loss test
3. Your CC's test is .5 or less
 
I am fairly confident of the CYA level of 50 (+/- 5). I tested again today to be sure. I'm no expert at that test but it should be close. It seems like I am losing a lot of chlorine during the day but the pool is in direct sun for most of the time. Today it dropped from 15.5 to 4.5 and the day before it was 36 to 15.5. But unless someone says otherwise I'll consider that normal. Perhaps the borates could help with my chlorine loss?

The water has always been crystal clear during the MA bloom. I am holding FC overnight and the CC is 0.5. So I guess I'm done shocking. In the end it was 8 nights at mustard algae shock level. Thank you to Brian for the note about getting behind the pool light. It was pretty foul back there. And possibly where it was hiding out during previous attempts to kill it off.

From other posts and the chlorine/CYA chart it indicates that I should keep my minimum FC at 7.5 for a few weeks. Going to add 2 large bottles of bleach now to get the FC back up.

I did see a small amount of something that could have been live or dead algae on the bottom of the pool near the return just now. Hopefully, the latter. Time will tell. Otherwise, the pool looks clean and clear.
 

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