Huge, Fast-growing, Happy Corals

Universal

Implementation has never been simpler. Add your favorite Calcium hydroxide Ca(OH)₂ powder and plug into any aquarium controller or timer and you’re all set.

Capacity

With 3 different models, there’s a reactor to suite your needs. Want to go longer between serving? Go with a larger reactor. Have a smaller system or don’t mind more frequent refills, go with a smaller unit. There’s really no wrong answer.
Z

Precision

Kalkwasser (kalk) is the easiest and least expensive Calcium and Alkalinity solution in the hobby, leaving more money in your pocket for hot corals.
U

Detail

Not only does Kalk help maintain a higher overall pH level to optimize calcification in corals, it also precipitates phosphates, helping you in the fight against algae.

Explosive coral growth and vibrant coloration

An MRC® Nilsen Reactor paired with an MRC® Calcium reactor is the ultimate combination for a healthy reef. Our design violently mixes the Kalk providing rock solid Ca levels, perfect pH, and amazing ALK stability.

Nilsen Reactors

Simply put, MRC® has brought the Nilsen (limewater) reactor to the 21st Century.  Using a powerful, external pump, the mixing is accomplished in a much more reliable way. These pumps are far more reliable and durable than internal pumps or stirring mechanisms often found in the market.

MRC® NR-1™ Nilsen Reactor
Overview

Up to 250 Gallons | Fully controllable | High Quality 3/8″ Cell Cast Acrylic & 1/4″ Cell Cast Acrylic tube 

MRC® Nilsen reactors are designed to perform straight out of the box. Using your current aquarium controller, you can quickly and easily program the frequency and duration of mixing . The external Blueline pump is easily accessible for simple maintenance. MRC Nilsen reactors are the most modern, simple, reliable, and beautiful Kalkwasser reactors on the market. 

Specs

Chamber Diameter OD: 4.5″

Height: 19.5″

Thickness: 1/4″ and 3/8″

Footprint: 6.5″ (10″ including pump)

Water inlet size: 1/4″ John Guest Speedfit

Water Outlet size: 1/4″ John Guest Speedfit

Method of feeding: Pump, powerhead, or gravity. *DO NOT CONNECT DIRECTLY TO RO/DI UNIT*

System capabilities: 250 gallons

Mixing pump: Sicce Syncra 2.0 HP (included)

MRC® NR-2™ Nilsen Reactor
Overview

Up to 500 Gallons | Fully controllable | High Quality 3/8″ Cell Cast Acrylic & 1/4″ Cell Cast Acrylic tube 

MRC® Nilsen reactors are designed to perform straight out of the box. Using your current aquarium controller, you can quickly and easily program the frequency and duration of mixing . The external Blueline pump is easily accessible for simple maintenance. MRC Nilsen reactors are the most modern, simple, reliable, and beautiful Kalkwasser reactors on the market. 

Specs

Chamber Diameter OD: 6″

Height: 19.5″

Thickness: 1/4″ and 3/8″

Footprint: 8.5″ (12″ including pump)

Water inlet size: 1/4″ John Guest Speedfit

Water Outlet size: 1/4″ John Guest Speedfit

Method of feeding: Pump, powerhead, or gravity. *DO NOT CONNECT DIRECTLY TO RO/DI UNIT*

System capabilities: 500 gallons

Mixing pump: Sicce Syncra 2.0 HP (included)

MRC® NR-3™ Nilsen Reactor
Overview

Up to 1,000 Gallons | Fully controllable | High Quality 3/8″ Cell Cast Acrylic & 1/4″ Cell Cast Acrylic tube 

MRC® Nilsen reactors are designed to perform straight out of the box. Using your current aquarium controller, you can quickly and easily program the frequency and duration of mixing . The external Blueline pump is easily accessible for simple maintenance. MRC Nilsen reactors are the most modern, simple, reliable, and beautiful Kalkwasser reactors on the market. 

Specs

Total Height: 19.5″

Chamber Diameter OD: 8″

Height: 19.5″

Thickness: 1/4″ and 3/8″

Footprint: 10.5″ (15″ including pump)

Water inlet size: 1/4″ John Guest Speedfit

Water Outlet size: 1/4″ John Guest Speedfit

Method of feeding: Pump, powerhead, or gravity. *DO NOT CONNECT DIRECTLY TO RO/DI UNIT*

System capabilities: 1,000 gallons

Mixing pump: Sicce Syncra 3.5 HP (included)

Find An Authorized Dealer

Purchase your +Series Nilsen Reactor from an authorized MRC® retailer today.
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