Product Review: DuoGuard Tablets

Duoguard Blog

Our new chemical line, GLB Chemicals, carries a chlorine tablet specially designed to provide extra strength algae prevention. This product, called GLB DuoGuard Tablets, is a 3-inch stabilized tablets containing a copper sulfate to fight algae, which is not found in standard 3-inch chlorine tablets. This provides extra protection against algae blooms, which helps keep your pool crystal clear. These tablets are also part of GLB’s Algae-Free Guarantee, so by using these with other Algae-Free products by GLB, you have a guarantee from the chemical manufacturer that you will not get algae, or you will be reimbursed.



  • Add one tablet per 10,000 gallons of pool water every week or as often as needed to maintain a chlorine residual at 1.0 to 4.0 ppm.
  • Use in a floating dispenser, automatic chlorinator or feeder designed for this product or place in skimmer. Use in a new chlorinating device or any device which has previously contained only this product or trichloro-s-triazinetrione.
  • If placed in the skimmer, run the pump a minimum of eight hours daily.


  • To provide optimum product performance, swimmer comfort and crystal clear water, always maintain pH from 7.2 to 7.6, total alkalinity from 80 to 120 parts per million (ppm), and calcium hardness above 200 ppm.
  • Test frequently using a GLB® 4-Way Test Strips that measures all these ranges.
  • Make any necessary adjustments promptly with the appropriate GLB pool care products.
  • Re-entry into treated pools is prohibited with chlorine levels above 4 ppm for risk of bodily injury.


  • This dosage may vary depending upon bather load, water temperature and other conditions.
  • Pool should not be entered until the chlorine residual is 1-4 ppm as measured with a reliable test kit.
  • As a preventative treatment, you should shock treat your pool once per week to prevent pool problems.
  • In addition to weekly shock treatment, you should shock treat to remedy problems which may occur when bathing loads are high, water appears hazy or dull, unpleasant odors or eye irritation occur, after heavy wind and rainstorms, or if algae does develop with resulting green color and slimy feeling.


  • Adjust pH to 7.2 to 7.6 with GLB pH Up or GLB pH Down per label directions.
  • Shock treat weekly with a product such as GLB Oxy- Brite® non-chlorine shock oxidizer, GLB Shoxidizer® non-chlorine shock oxidizer or GLB SuperSonic to kill bacteria, control algae, burn out organic material and to keep water sparkling clear.
  • Follow label directions.


  • If pool surface develops algae or feels slippery, follow shock treatment directions.
  • Immediately after shock treatment, thoroughly clean pool by scrubbing surface of algae growth, vacuum and cycle through filter.
  • If necessary, repeat the procedure.
  • Pool should not be entered until the chlorine residual is 1-4 ppm.

So if you are looking for the easiest way to prevent algae, be sure to try GLB DuoGuard Tablets. By simply switching the type of tablet you are using, you can greatly increase the long-term clarity of your pool water. Have you tried DuoGuard tablets before? Let us know how they worked for you in the comments below!

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