The Calciumreactor KR Blue is a hermetically closed system with an integrated circulation pump and CO2 return. It can be mountedin a bypass, indpendent of the water level of the aquarium or filter sump. It comes filled with 8 lbs. Hydrocarbonate. The addition of CO2 lowers the pH value in the KR Blue and the hydrocarbonate dissolves. Despite the low flow rate of app. 0.25 – 1 gph, high amounts of calcium and bicarbonate ions are delivered into the aquarium, which is highly beneficial to the aquarium inhabitants. The KR Blue is supplied with a port for a pH probe (PG 13.5). Rated for 65 gal. to 270 gal. aquaria.