Congratulations on your purchase of the MRC Nilsen Reactor; the world’s finest and most
robust kalkwasser reactor.
A Nilsen Reactor, like a calcium reactor, helps dissolve calcium into a useable form before
distributing it into your aquarium. However, a Neilson Reactor uses a separate chamber to
mix kalkwasser (saturated limewater) into the water; no carbon dioxide is needed.
Kalkwasser is made by dissolving calcium hydroxide powder in fresh RO water to produce
a limewater solution that contains free calcium and hydroxide ions. This solution, however,
is highly affected by the CO2 in the air, reducing the calcium levels significantly. To prevent
this degradation of the solution, an airtight reactor is required.
The Nilsen reactor is a long time favorite of reefers for the simplistic approach to topping off
with fresh water and raising Ca levels at the same time. Kalkwasser also has the added
benefit of precipitating phosphates from the water column, stimulating SPS growth, and
hindering algae growth. Because of the high ph of kalkwasser, approximately 12.0, the
Nilsen reactor can be used to counteract the low ph of a calcium reactor’s effluent.
Required Equipment
For proper operation of the MRC Nilsen Reactor, you will need additional equipment:
An auto-top off device (float switch with solenoid and pump) or
A dosing system (LiterMeter, etc.)
A supply of RO water
Aquarium controller or timer
The auto-top off unit will monitor the water level within the aquarium and replace the
evaporated water with fresh RO water. The RO water will pass through the Nilsen Reactor,
pushing out the kalkwasser solution as it enters the unit. As the kalkwasser solution exits
the reactor, a fresh batch of RO water is introduced, ready for the Nilsen Reactor to mix
with the calcium hydroxide powder.
Under no circumstances should you connect the Nilsen Reactor directly to a RO/DI
unit. Doing so may result in consequential damage to the reactor, voiding any and all
warranties.
Operating Instructions
The MRC Nilsen Reactor is a very simple, yet powerful system.
Inspect the reactor for shipping damage and contact your dealer with any issues.
Place the reactor in its permanent position. It is best placed outside of the sump.
Attach the pump and hand tighten the unions making sure the o-rings are in place;
make a secure seal. Connect the pump to your timer or controller.
Fill the reactor approximately ¾ full with your top off water.
Slowly add Kalk powder (calcium hydroxide) to the reactor.
Small & Standard Nilsen – 2 cups
Large Nilsen – 4 cups
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Care should be taken not to inhale the calcium hydroxide powder/dust.
Also, the freshly mixed solution could stain clothing or irritate skin. Please
check with the powder manufacturer for details and precautions.