KS100 Kalk Stirrer (Nilsen Reactor) - Reef Octopus

Reef Octopus KS100 Nilson Kalk Stirrer
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KS100 Kalk Stirrer (Nilsen Reactor) - Reef Octopus

100% Recommend this to a friend (2 of 2)

SKU: 207889
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Quick Overview

Nilson Reactors will help automate the addition on kalkwasser by gently mixing and stirring kalkwasser with your top off water creating a super saturated slurry.

  • Rated for aquariums up to 120 gallons

  • Push-connect fittings

  • Kalk stirrer body with stirrer pump

  • Quiet operation

  • Requires feed pump and control timer


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Product Questions

How often do you need to refill the reactor
Question by: Darrell Booker on May 4, 2016 3:14:00 AM
Great question!
When used in conjunction with an ATO the water will not need to be refilled rather the Kalkwasser will need to be added in when ever the kalkwasser power in the bottom is not visible to be tumbling. Typically once a month the refill will need to occur. Feel free to let us know if you have any further questions!
Answer by: Connor (Admin) on May 4, 2016 12:40:00 PM

Full Details

Reef Octopus KS100 Kalk Stirrer Manual


Kalkwasser dosing is considered one of the best all around methods to supplement calcium and alkalinity in a balanced solution. Pushing your top off water through a Nilson Reactor will create a super saturated slurry that has a high pH, helping increase your tanks pH while keeping your reefs most important elements (calcium and alkalinity) stable and balanced. There are many different dosing methods for kalkwasser, and by using a reactor, you can go longer in between maintenance while keeping a very stable, and consistent solution.


When adding kalkwasser to any aquarium, it is best to use a pump with a slow flow rate. Due to the high pH of the solution, it is best to add kalkwasser in small amounts, slowly, multiple times a day. Most ATO systems on the market will fit the flow rate needs of the reactor very nicely.  A timer for the stir bar motor is required to mix the solution throughout the day. We suggest the reactor mix just a few times a day for just a couple of minutes.


More Features:

  • Solid construction
  • Push connect input and output: 1/4"
  • Designed to keep large particles in bottom of chamber with saturated solution at top
  • Large thumb screws to easily release lid

Reactor Specifications:

  • Body Diameter: 4”
  • Height: 27.25”
  • Footprint: 5.25” x 5.25"
    • Note: Requires control timer and feed pump. The Kalk Stirrer uses a 20w motor that has a lifetime of about 1500 hours.


      Manufacturer's Warranty

      • 1 year on reactor body


      Item #: OCT-KS100



2 Items

  • Update: mixing is too slow By Joe on 2/3/2014

    This is an update on my review on 1/25/2014.

    After running the reactor for a short time now, I have found that the stirring rate of the Ca(OH)2 is too slow (motor runs as 2.5 RPM). For my system this is insufficient to mix the incoming DI/RO water with the Ca(OH)2. Over time, the pH of the kalkwasser leaving the reactor drops to less than 11. Saturated Ca(OH)2 solution at 25 C should be around 12.4. This is with running the motor for more than the suggested duty cycle (10-15 min out of ever 120 min).

    I am currently looking to replace the motor with one that spins faster, like 50 RPM.
  • very well made, works well By joe on 1/25/2014

    I've only been using this for a few weeks so far. The unit is very well designed and manufactured. I'm using a Toms aqualift, and there is no chance that particulate Ca(OH)2 will be lifted out of the unit at such a low flow rate. You could probably go even with a little higher flow rate that what the Toms pump can do and still have not problems.

    I also run a Ca reactor, so this unit is setup only to add ATO water at night, which allows me to keep the pH up above 8.2 all the time. It's also clear now that I must have had some CO2 dissolving into my kalkwasser solution before, as the ATO+kalkwasser was not as good at raising my pH at night as using this reactor. Of course, I don't have to mix up big batches of kalkwasser anymore either, but I'm still using an ATO reservoir (just DI/RO now). I may setup it up for direct connection to the DI/RO system.

    Only concerns are:
    1) They indicate that the motor only has a 1500 hr lifetime, which is extremely short. They recommend running the motor on ~15 min out of every two hours, but if you did this 24/7, the motor would only last a little more than a year. So, I only run the motor when the ATO pump is on, which really only comes on for perhaps 15-30 min per day. This seems to work fine for my setup (~60 gal system, but lots of surface area, so evaporates ~1.5 gal/day).
    2) They should supply the unit with a check valve; otherwise, you will have water flowing back into your ATO reservoir. Make sure to get a check valve with this.