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Thread: mustard algae

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    mustard algae

    I've got a greenish/yellowish dust all over the bottom of the pool that brushes up quite easily, but makes the whole pool look green. It appears to be mustard algae. I just found this board, so I'm eager to stop wasting money at the pool store. My first attempt was to shock the pool with 2 bags of powder shock (10,000 gal per bag), then use a product called Yellow Out which I have had success with in the past. That didn't work, so I went back and applied 4 bags of shock and a product called Suncoast All in One Algaecide. I first added the 4 bags of shock, waited a day and then added the algaecide and let the pump run 24 hours. Followed by 2 more bags the next day. I brush the pool twice a day to remove the dust.

    I'm not having much success. I replaced the Cartridge filter at the end of last season, so it is pretty new and I maintain a filter pressure of about 20psi which is the recommended level. The pool store is too expensive to keep dumping in chemicals that aren't working.

    As a followup question, here in Florida, it tends to rain in a large burst and then go away. My pool can fill up an inch or more on any given T-storm. This tends to start the algae process. I have a Chlorinator that I keep 5 cakes in that is usually set to 4/5 and maintains a good chlorine reading, however these storms seem to overwhelm my system. Should I toss a bag of shock in when a storm rolls in? Anyway to avoid this?

    What are my next steps?
    I have a 19,000 gallon, gunite - white, Cartridge filter, chlorinated pool (no salt).

    Readings:
    FC - 4.0
    stabilizer 100
    CYA - 60
    CH - 600 - This reading was weird because I went to two pool stores and one told me it was 280 while this one said 600.
    TA - 120
    pH - 7.5

    thank you
    7000 gallons
    above ground 12x24 oval
    vinyl
    16" sand filter
    1 1/2 hp pump
    Destin/Fort Walton Beach Florida

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    JasonLion's Avatar
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    May 2007
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    Silver Spring, MD
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    Re: mustard algae

    Welcome to TFP!

    You say stabilizer 100, and CYA 60. But stabilizer and CYA are the same thing. If CYA is really 100, that could be the problem right there.

    Mustard algae, and pollen tend to look confusingly similar. Mustard algae tends to grow on the bottom and walls of the pool only on the shady side of the pool. While pollen tends to collect on the floor, but not the walls, and appear everywhere regardless of shade. Mustard algae will also go away while you have the FC level high, while pollen will come back even when FC levels are high.

    Also, it would be a good idea to do some reading at Pool School.
    19K gal, vinyl, 1/2 HP WhisperFlo pump, 200 sqft cartridge filter, AutoPilot Digital SWG, Dolphin Dynamic cleaning robot
    Creator of PoolMath and Pool Calculator. Other handy links: Support this site, TF Test Kits, Pool School

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    ivyleager's Avatar
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    Sep 2007
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    Raleigh-Durham,NC
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    Re: mustard algae

    Hello and welcome!

    First things first: you really need to get your own test kit. So much more reliable.

    Second, I'm assuming that the bags of shock are calcium hypochlorite, which is a decent chlorine source but will also add calcium to the water. This could explain your quite high CH reading. You may be better served using liquid chlorine (bleach) as your chlorine. HOWEVER, do not use liquid chlorine when you have cakes/pucks in the chlorinator. This could cause an explosion and is BAD!

    Third, stabilizer and CYA are the same thing so not sure about those readings. But, I'd wager that if you are using cakes/pucks then the stabilizer/CYA is nearer to 100, and if so then your FC needs to be closer to 8 for maintenance.

    JasonLion is right: you'd be well served to read pool school http://www.troublefreepool.com/categ...pool_chemistry We all started there and takes some time to integrate all the information, but it's spot on accurate information.

    Hope this helps.
    CaryB
    36 x 18 IG vinyl, 25K, 1 HP pump, sand filter
    1 skimmer, 2 returns, no main drain
    Old school: PoolSolutions test kit

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    Re: mustard algae

    Thanks Jason and Cary,

    I got 2 readings from 2 different pool stores. The first sheet listed Stabilizer with an ideal range of 40-100ppm and told me it was at 100. The 2nd listed CYA with an ideal range of 30-50ppm and that value was listed at 60, so I'm not sure if these 2 readings should be the same or if their tests were different since their ranges are different. In any case, I need to invest in my own quality kit.

    I'm pretty sure it is mustard algae. It is growing on walls and bottom of the pool in all areas (not just shady). It's pretty much everywhere. I was brushing it off the light and tiles too.

    I will check out the pool school. Still have to get my own terminology down too.
    7000 gallons
    above ground 12x24 oval
    vinyl
    16" sand filter
    1 1/2 hp pump
    Destin/Fort Walton Beach Florida

  5. Back To Top    #5
    JasonLion's Avatar
    Join Date
    May 2007
    Location
    Silver Spring, MD
    Posts
    37,879

    Re: mustard algae

    Yes, CYA and stabilizer are the same thing, despite the difference in recommended range. At least one of the store CYA test results is wrong, possibly even both of them.
    19K gal, vinyl, 1/2 HP WhisperFlo pump, 200 sqft cartridge filter, AutoPilot Digital SWG, Dolphin Dynamic cleaning robot
    Creator of PoolMath and Pool Calculator. Other handy links: Support this site, TF Test Kits, Pool School

  6. Back To Top    #6
    ivyleager's Avatar
    Join Date
    Sep 2007
    Location
    Raleigh-Durham,NC
    Posts
    489

    Re: mustard algae

    Quote Originally Posted by neilg
    Thanks Jason and Cary,

    I got 2 readings from 2 different pool stores. The first sheet listed Stabilizer with an ideal range of 40-100ppm and told me it was at 100. The 2nd listed CYA with an ideal range of 30-50ppm and that value was listed at 60, so I'm not sure if these 2 readings should be the same or if their tests were different since their ranges are different. In any case, I need to invest in my own quality kit.

    I'm pretty sure it is mustard algae. It is growing on walls and bottom of the pool in all areas (not just shady). It's pretty much everywhere. I was brushing it off the light and tiles too.

    I will check out the pool school. Still have to get my own terminology down too.
    We here at TFP are pretty adamant about investing in a test kit. By doing your own testing, you get accurate and trustworthy results. East to go from there.

    If your CYA is 100, it's gonna be tough to beat the mustard algae. With higher levels of CYA, you need higher levels of FC. It may be best to do a partial drain and refill. AND YOU NEED TO STOP USING PUCKS!!! They add CYA to the water. When you use bleach, nothing else is added to the water.

    ****But you can't use bleach with pucks in the chlorinator. Danger danger! Get the pucks out and turn it OFF.

    I just got over a nasty battle of mustard algae and used Yellow Klear (same as Yellow Out). However, with that chemical you need to have plenty of bleach on hand because it'll burn through it VERY quickly. I battled for a solid month: shocked to recommended Mustard algae level, held for 48 hours and when FC returned to maintenance level, it was back. Did this 2X. After Yellow Out - nothing since. I used it as a last resort.
    CaryB
    36 x 18 IG vinyl, 25K, 1 HP pump, sand filter
    1 skimmer, 2 returns, no main drain
    Old school: PoolSolutions test kit

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