My battle with Mustard Algae

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jeninok

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May 29, 2012
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I am at work right now, so I don't have the numbers for our pool, but we have been battling mustard algae off and on for several weeks now. I do know our CYA level is about 50, and on a daily basis I try to keep chlorine at about 4ppm, due to dirty kids, lots of wind and what were incredibly hot temperatures for weeks at a time.

I think a couple of times due to weekend trips it must have dropped too low and let the algae get started, normal shock levels of 15 ppm would knock it out, but it would come right back as soon as we dropped back down to normal levels.

So for the last 4 days I have been keeping the chlorine incredibly high, I forget the PPM that the pool calculator told me to use for mustard algae, but I believe it was 296 oz. of Bleach for my 15foot intex pool, to go from 5 ppm to Mustard algae levels

Finally the water is not yellow or green, but it is cloudy as heck. Yesterday morning, after vacuuming to waste as much as I could, I cleaned the filter, added bleach to get back up to Mustard Algae shock levels, let the pump run all day and then added a dose of clarifier to try to get some of the super fine muck to stick together.

I also soaked and scrubbed all pool equipment, ladders, toys etc etc.

I plan on keeping the shock levels up another 24 hours, then checking for OCLLT, and balancing PH and all that good stuff.

Here is my problem, we are leaving Friday afternoon and won't be back until Sunday night or Monday morning. I am worried that by leaving the chlorine levels will drop too low and the algae will come back!! We are going with our whole family that is in town, and I really don't know if there is someone I can get to come by and dump bleach in the pool???

Any ideas?
 
Yes we did pass all three criteria each time, but then within days of normal chlorine levels the super fine slimey yellow dust along the bottom edges, in the small creases and along the bottom of the skimmer basket. This cycle has happened twice so far, and I just want to swim! I have also stuffed the middle of the intex cartridge with fishtank filter fluff, and am putting cut up bar towels in the skimmer, removing, and washing in hot bleach water each time.
 
Also, this seemed to start right at the same time our city added Chloramine to the water purification system, and in general, our area water has high phosphates due to chicken waster and fertilizer run off, that used to cause me all sorts of issues with my fishtanks.
 
The first thing that popped out at me was saying you keep the FC at 4ppm in a 50ppm CYA pool. 4ppm is the MINIMUM it should ever get. Given that "most" pool loose 2-4ppm of FC per day, you likely should be boosting the FC to about 8ppm everyday so that it does not drop below 4ppm by the next day.

What are you using to maintain the FC level?
 
This is long...I'm not at work anymore so I will try to fully explain the situation.

We have been through the shock process twice before, those times the issue was milder, and after passing all the criteria would be fine for a week or so, then slowly start to get the dusty stuff, I honestly thought it must be pollen or dust since we had shocked and passed the tests. This last time it went from clean to nasty in a matter of two days.

We use bleach, 6% following the pool calculators amounts. Until the clarifier I used last night, I have never put anything but liquid bleach, borax and CYA in the pool. We clean the filter a couple times a week, and change them out when they start to look gross. The filter needs upgraded, but with only a month and half left to swim it isn't my top priority right now.

This morning the pool was blue again, but cloudy. We left the pump off for a few hours to let things settle, once settled the water was nearly clear almost to the bottom, without the sickly yellow tint it had before. I just re tested everything and it stands at
FC 24
CC..dunno i forgot to test
CYA 30 (this is closer to what I expected it to be, I wonder if the cloudy water messed up my test last time.)
TA 120
CH 240
PH 8

I know the PH needs to come down a lot, and I have also read that adding a Vitamin C tablet to the bathtub, or floating some fruit in a pitcher of water is a good way to get rid of the newly added Chloramines in our drinking water. I assume that a lower PH in the pool will also help combat the issues it might be causing?

the horrible heat wave with weeks of 100+ weather and no rain seems to have broken, I am hoping that might help get this under control, plus we shouldn't have to keep topping off as much, which might be where I have gotten my numbers confused and not kept proper levels :oops: :oops:

Two days ago there was visible yellowy brown scum everywhere, the skimmer was pulling in lots from the surface of the water, and it was coating basically the entire bottom, worse in the shady areas.

I cleaned the filter and wrapped it in a knee high, cleaned the skimmer and put fresh bar towels in it, brushed the pool as best I could and then got in and walked in circles. After it all settled I vacuumed to waste moving slowly to try not to stir things up again. The stuff that comes out is super super fine, yellowish brown, and slightly slimy.


I also way overshot the chlorine for the last 2 days assuming my CYA reading of 30 is right. I would have expected the levels to be much higher??

Thankfully the liner color seems ok, even after the ridiculously high bleach levels the last few days, but honestly at this point I don't care about fading it some, I just want to kill whatever is in the darn pool.

Should I aim to keep the Chlorine levels at 24/25 since it seems to be working?

What about this weekend when we are gone, I am worried it is going to explode again if we aren't here to keep dumping bleach.
 
Here is what I would do, it basically follows the Mustard Algae Pool School Article:

1. Follow the normal shock process again until you pass all three criteria.

2. Raise the FC up above the Mustard level for 24 hours. If your OCLT still pass and you have <0.5 CC then let it drop down to normal levels.

Do not adjust ph while you are over 10 ppm FC, it's reads high.
 
Okay, I will keep on it.

I am wondering if I should put a puck in the skimmer this weekend, or should we just raise it to shock levels friday before leaving, the retest and raise as needed sunday as soon as we get home?
 
You should only even consider putting a puck in the skimmer if you are going to leave the pump on the entire time. A puck in the skimmer with the pump off is bad.

Since your CYA is on the low end, you could get away with adding some pucks to help maintain the FC while you are gone. You are in the shock process anyway, so certainly raise the FC up to at least shock level ... and optionally put the pucks in as well.
 
Just to be clear - what was your target FC after the previous shock processes were comleted? Were you aiming for 4 or was 4 your minimum? Do you think it could have dropped below 4 at any time?

With CYA between 50 and 30 there is a bit of variation here but let's assume 40 for the sake of discussion. Anything under FC=3 would be an opportunity for trouble to restart.
 

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We run the pump 24 hours a day unless we turn it off to let things settle for cleaning purposes.

Also, does the addition of chloramine to the city water have any bearing on pool chemistry? I thought that chloramines were what we were trying to avoid since it means there is less available FC to work.
 
No, the chlorimines disappear pretty quickly, though they do use up a little more chlorine to get rid of them.

jeninok said:
We run the pump 24 hours a day unless we turn it off to let things settle for cleaning purposes.
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Do you run 24/7 when not shocking? If yes, I would consider a 2-speed pump (if you do not already have one) or reducing your run time...it is unlikely you are getting much benefit from the 24/7. Again, I am referring to when you are not shocking.
 
I will figure out how to add my info to my signature ")

We run it so much because it is so small, and it has been so hot. Without the pump the pool gets really gross, and the water gets even warmer.

I know it isn't enough water flow for the pool and that is a lot of our problem, but we had to buy a new (used) car a few weeks ago and we just don't have it in the budget to replace the filter and get the adapters and such.
 
That was easy!

I just went outside to look at the pool and it looks much much better than it did this morning, I used the broom to swish up bottom so the filter can get to it better, and replaced the cloth in the skimmer. I will retest soon, and see where the FC is, it looks like rain is on the way so I want to make sure we don't drop too much.
 
Thinking ahead to the weekend, do you have a cover for the pool, if not, can you afford to buy one? The cover will help protect the chlorine from the sun while you are away and you might not lose too much ground that you have gained on the algae. I recommend getting a blue bubble cover. The cost of the cover might be saved with all the time and bleach that you already have put in.
 
I actually just talked to my husband about that and we are wanting a blue solar cover anyway to help extend our season, I think I will pick one up in the morning.

The water is looking better by the minute, still cloudy, but when I brush the bottom barely anything comes up, and there is no fine scum in the skimmer.

But its about to rain, I just tested and my Fc is 22, should I add some bleach now, or wait until after it rains? I don't want to fall too low at any point and have this stuff come back.
 
ping said:
Thinking ahead to the weekend, do you have a cover for the pool, if not, can you afford to buy one? The cover will help protect the chlorine from the sun while you are away and you might not lose too much ground that you have gained on the algae. I recommend getting a blue bubble cover. The cost of the cover might be saved with all the time and bleach that you already have put in.
jeninok said:
I actually just talked to my husband about that and we are wanting a blue solar cover anyway to help extend our season, I think I will pick one up in the morning.

The water is looking better by the minute, still cloudy, but when I brush the bottom barely anything comes up, and there is no fine scum in the skimmer.

But its about to rain, I just tested and my Fc is 22, should I add some bleach now, or wait until after it rains? I don't want to fall too low at any point and have this stuff come back.
Click to expand...
Click to expand...

There have been multiple discussions about this and what I read says DO NOT cover during shock process. The sunlight is needed to help break down the CC's. Indoor pools have trouble breaking down CC's because they get no sunlight - this is a small example of this same thing.

Also clear - not blue - is the color most people swear by for solar heating. However not having the cover on at all during sunlight is best from the tests I have seen. The cover is most useful to prevent heat loss after/before the sun hits the pool.

Lastly what I read says that rainfall should not be an issue in most cases - assuming you have enough FC to begin with.
 

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