Check the listing for details. Reef Reactor Medium (4 L) Calcium Reactor Media - Seachem. Condition: New. Listed at 32.52 USD. Reef Reactor™ is a high-purity source of aragonite, which supplies all important elements for optimal ionic balance and robust coral growth and coloration in reef aquaria. It has a grain size of approximately 0.5–1 cm (Reef Reactor™ Lg is 1 - 3 cm). It is intended for use in calcium reactors where it is dissolved slowly with the addition of CO2. As it dissolves, it provides calcium, magnesium, strontium, potassium, and carbonates among other important elements for reef aquaria. It is excellent at increasing and stabilizing alkalinity, which also supports a stable pH and encourages the rapid formation of coral skeletal material. With high levels of both calcium and magnesium, it offers an excellent means of balanced supplementation for rapid growth and propagation of corals and calcareous animals in reef aquaria. It possesses the highest level of soluble potassium of all competing brands while exhibiting the lowest levels of both aluminum and phosphorus. Listing and template services provided by inkFrog