One full bottle of Spa Marvel treats any tub up to 500 gallons (2000 liters), and lasts 3 months with regular use. Every 3 months simply add another bottle of Spa Marvel Hot Tub Water Treatment & Conditioner.  In a swim spa use 1 bottle once a month.  In a swimming pool use Pool Marvel.  You do not need to change the water as often as you typically would because you are not super-saturating the water with all kinds of chemicals on a routine basis and the TDS (total dissolved solids) of the water increase only marginally. Change your water as per your professional spa retailer’s guidelines, or when your Total Dissolved Solids (which your retailer can measure for you) approach 2,000 ppm, and do not go past 1 year without changing.  It is, however, good practice to change water every 3 months.

The natural enzymes for hot tubs contained in Spa Marvel are derived from plant extracts. Unlike chlorine, which sanitizes and essentially attacks and kills bacteria, these natural enzymes for hot tubs help to remove the food (organic waste) necessary for bacteria to live, which is in part how lakes and aquariums maintain themselves without using chlorine.