Pool Marvel - by Spa Marvel A Product that pool owners love to use: - Dramatically reduces pool maintenance. - Helps to improve water clarity and quality. - Enhances chemical treatments. - Helps to maintain pH and alkalinity levels. - Reduces scum lines, chlorine odours and irritated eyes. - Improves filtration. - Just one capful (100 ml or 3.3 ounces) treats up to 20,000 gallons (75,000 litres) of pool water per week.