Active Aqua's chillers are (they use R134Aa refrigerant) and are ideal for keeping the nutrient solution in your reservoir at the perfect temperature. Can also be used to chill your cold plunge bath water.Each unit has a user-friendly temperature system that allows you to control your desired temperature range as needed, and all models now have a boost function that accelerates the chilling process for quicker establishment of initial nutrient solution temperature. Features: Large refrigeration capacity (recommended volume: 40 gal to 92 gal ); Anti-corrosive pure titanium evaporator for both fresh and salt water; Rate of flow: 1/4 HP (396‒925 gal/h -1500‒3500 L/h); Rated BTU per hour: 3, 010; Recommended pumps: AAPW400 or AAPW550 or AAPW8001/2" and 3/4" fittings includedUnit dimensions: 18"L x 13"W x 17"HFor cooling capability, please refer to performance chart found in the product information tab Please note that the starting ambient temperature of your solution will always affect the duration of the initial chilling process.