Yellow Treat®


The Fast and Easy way to Kill Mustard Algae. Guaranteed.

  • Kills the toughest mustard algae fast
  • Requires less shocking
  • Safe for all types of pools

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Product Description

The Original Mustard Algae Killer

Yellow Treat® is the original mustard algae killer.  Introduced in 1981, Yellow Treat® has become the most trusted answer to yellow algae.

  • Kills Mustard Algae Fast: Yellow Treat®’s powerful formula kills mustard algae fast. In as little as 24 hours it will turn a yellow pool back to clean.
  • Less Shocking: Yellow Treat® requires less shocking to get the job done. This saves you time, money and hassle.
  • Safe for any pool: Yellow Treat® is tough on algae – not on surfaces. Meaning it’s safe for any type of pool. It also contains zero ingredients that stain. Keeping your pool looking beautiful after the algae is gone.

100% Performance Guaranteed

All our products are backed by a 100% Performance Guarantee. If this product doesn’t solve your problem we’ll fix it for free or you get a full refund.

Additional information

Weight 2 lbs
Dimensions 3.25 × 3.25 × 9.25 in
Product Type

Rescue Algicide


5 oz. bag, 2 pound bottle


5 oz. per 10,000 gallons

Surface Compatibility

All Surfaces

Sanitizer Compatibility

Chlorine, Salt and Bromine

Questions & Answers

  1. 0 votes

    If you happen to overdose on the Yellow Treat, you'll just need to increase the amount of shock you use to bring it into a proper ratio. Just repeat the shock treatment and everything should be okay. If you still have any issues, you can open a support ticket with us.

  2. 0 votes

    It sounds like what you may have is scale - if it looks like a hard crusty buildup. In that case you may want to checkout CalTreat. Otherwise, if it's algae, yellow treat should kill it.

  3. 0 votes

    What you're likely seeing is the reaction with chlorine. It's normally and should go away quickly. Might also indicate that your water has slightly high level of metals.

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Customer Reviews

2 reviews for Yellow Treat®

  1. Avatar


    Is it okay to use Calcium Hypochlorite with this product?

  2. Avatar

    Jim Guyton

    Yellow Treat completely removed mustard algae from my pool. However, I get a zero reading for chlorine, and I have added 5 pounds of shock chlorine.

    • Avatar

      Scott Hamilton

      This can happen depending on your type of chlorine. I would chlorinate as normal and use an OTO test for the chlorine (they are more accurate). I wouldn’t advise to continue to shock, since this can cause staining (and can be expensive). Although your test is giving you a zero reading – the pool shouldn’t develop algae (it’s more of a false reading). If the problem hasn’t subsided in a week, call us and we can diagnose why your pool is continuing to have this problem. Thanks!

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