Algae Growth
Algae growth in spas is fairly uncommon, unless the spa is outdoors and not used often. To prevent algae growth, maintain proper sanitizer level consistently and circulate the water several hours daily.
If algae is present, add 2 tsp. of brominating or chlorinating concentrate per 100 gallons. A spa shock or oxidizer may also be used. Circulate several hours. Clean the filter after treatment. More than one application may be necessary.
Note: This information is intended for a residential spa with average use. It is not designed for public, commercial, or semi-public spas. If your hot tub is used more than three times per week, you should check and make chemical additions more often than suggested.