Mustard Algae

[eluded]

First post, just want to say this board has been great. Just found it earlier this year, so this is the first year I will be taking control of my own pool instead of being "pool stored." Been going great so far, I purchased the TF-100(great kit ) been doing my own tests which have matched up pretty good to the pool stores test. I just wanted to double check myself.

I've had a problem with mustard algae for the past 3 yrs in a row. This year I want to get rid of it once and for all. So far I have been following the shock procedure for 4 days now and the water is crystal clear. My FC levels are still dropping, so I am going to continue the process. Just wanting to know if I should go ahead and bring the FC level to the mustard algae level now since my water is clear, or wait until the FC level holds overnight? Right now I am losing about 1ppm/hr with the SWG running at 80%. I do still get a couple of spots coming back, they are more white to gray in color than before. Vacuuming them up at least once a day. Could this still be algae that is consuming the FC even though the water is so clear?

Latest test results
FC 31
CC 0
CYA 80
TA 100
Salt 3400
brought Ph down to 7.2 before bringing FC up, not sure what it is now(didn't think it would be accurate)


Sorry it's so long, just wanted to give as much info as possible. Questions in blue to make it easier. Pics attached, algae spot, deed end to show clarity of water, and overall pool.

 

[duraleigh]

You should perform the OCLT (shut off your SWG first) and see if you are losing any Chlorine overnight....I bet you are.

Two things consume chlorine in a pool....

1. Sunlight

2. Organics (including algae) in your pool water

The OCLT will prove or disprove the presence of organics.

Mustard algae is characterized by a yellow-greenish very light coating on the pool walls and floors. When brushed it quickly poofs away like dust but then regrows VERY quickly. What you are describing doesn't look or sound like mustard algae.

You still need to perform the OCLT regardless of the "brand" of algae you have.

 

[eluded]

Thanks for the quick reply, that's why I love this site. The algae was doing that exact thing before I started shocking. That pic was after 4 days of being at shock level. Mostly on floor, then started on the slopes from wall. At first I wasn't sure if it was algae or pollen at first, but when it started climbing figured it was algae. I did the OCLT after the water cleared up and lost 4ppm. I will redo it tonight. Thanks again.

 

[duraleigh]

I do still get a couple of spots coming back, they are more white to gray in color than before.

That's what tricked me. Mustard algae doesn't present in spots not does it turn white or gray. That said, if it is acting like the description in my other post, that's what you have.

 

[eluded]

Sorry for the confusion, I just figured the spots that are reappearing are dead algae. Or at least hoping so. If I don't pass the OCLT, should I bring the FC level up to mustard shock or leave it at regular shock until I pass the OCLT?

 

[duraleigh]

bring it to mustard just to be safe....not that much more chlorine.

 

[eluded]

Thanks, will bring it up in the morning after I retest.

 

[eluded]

Lost 2ppm overnight, so brought up to 44 per pool calc. Hopefully I am nearing the end soon. I plan to keep the FC up in this range until it holds overnight. After it holds overnight, should I keep it there another 24 hours as per pool school for mustard algae?

 

[duraleigh]

You know, losing only 2ppm suggest you have very little organics left. I think if it were my pool I would (I'm flip-flopping) let it return to normal shock value and do the OCLT Tuesday night.....I'll bet you pass.

Have you brushed and gotten rid of those spots. It's gonna' take some scrubbing to get them loose, I think.

 

[eluded]

I've been using vac to clear up spots that come back and brushing daily. They disappear with the vac no problem and if I just use a brush they dust up and disappear. Maybe some of it is pollen, but the chlorine loss was throwing me off.

 

[eluded]

I just re-tested after bleach addition 1.5 hrs ago, FC 44-44.5 (slightest pink tint before extra drop). You think I should just let the FC level fall by leaving SWG off and not holding at this level for 24hrs? I will be leaving for work in about 2 hrs and won't be able to retest until after dark.

 

[Bama Rambler]

I'm gonna take a different tac than the other Dave. If I suspected mustard algae I'd hold it at mustard shock level until I passed the OCLT two nights in a row. That's just me and how bad I hate algae, especially mustard algae.

 

[Butterfly]

And, this stuff, too:

While at mustard algae shock level you need to throughly brush the entire pool, including walls, floor, steps, skimmer, under ladders, everywhere. All pool tools and toys and anything else that is used in the pool needs to be wiped down with a dilute bleach solution or soaked in the pool for an hour while at mustard algae shock level. Bathing suits should be run through the laundry. If you have underwater lights, they should be removed from their niche and the niche brushed out, and then the lights replaced. If you have fountains, or waterfalls, or other water features, they need to be run for at least an hour while at mustard algae shock level. Be very thorough, or you will most likely just need to do it all over again.

 

[eluded]

Thanks for the replies, that is kinda what I was thinking i should do. Just trying to get a hold of all this stuff. I've had to deal with this problem for the last 3 yrs in a row, last yr being the worst(3 outbreaks). Would like to get rid of it once and for all if it is truely algae and not just pollen. I've always just followed what the pool store told me to do, but I am really liking the BBB method much better.

Will it be ok for me to get into the pool and do some good scrubbing with the chlorine levels this high?

 

[chem geek]

Even at 44 ppm FC with 80 ppm CYA, the active chlorine (hypochlorous acid) level is equivalent to 1.3 ppm FC with no CYA. You don't want to drink large quantities of pool water since the FC will be so high, but in terms of your swimsuit, skin, hair, etc., it won't be much different than being in a commercial/public indoor pool that typically doesn't use CYA. It's not something we'd recommend for swimming, but for getting in to scrub or to remove the light to get chlorine exposure into the light niche, it won't harm you. Your exposure will be relatively brief in any event.

 

[jordangregory]

This all sounds like my pool last year. I had the yellow greenish light coating that poofs away like dust and came right back. I don't think I ever got rid of it. This thread has really motivated me to get rid of this stuff at the beginning of the season!

 

[eluded]

This all sounds like my pool last year. I had the yellow greenish light coating that poofs away like dust and came right back. I don't think I ever got rid of it. This thread has really motivated me to get rid of this stuff at the beginning of the season!

Good luck to you on this endeavor. Just make sure you have a ton of bleach, I am going through it like crazy.

 

[MNPoolDreamer]

I thought mustard algae only grew in the shade. The circled spot in the picture appears to be in a sunny location.

 

[eluded]

I thought mustard algae only grew in the shade. The circled spot in the picture appears to be in a sunny location.

The only shade my pool sees is first thing in the morning while it is shaded by the house. Doesn't last very long though.

 

[chem geek]

If the spot with what you think is algae is exposed to a lot of sun, it is unlikely to be yellow/mustard algae as it prefers shade even to the point of growing in light niches or under removable ladders as well as the shady side of the pool. The spot might be something else, even pollen.