Precision Marine Kalkreactor KR620

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Precision Marine

At Precision Marine there are two ways Calcium can be added to your reef tank, the Calcium Reactor or the Kalkreactor pictured here. You can either gravity feed through the Kalkreactor from a freshwater top-off system to your reservoir, or use a dosing pump.

A reliable water pump is used in lieu of the magnetic stir bar, which tends to jam, bind and wear the acrylic.

This model also includes a threaded opening at the top to enable adding Kalk powder without removing the lid.


KR620 Specifications:

  • Overall Height: 20"
  • Reaction Tube Diameter: 6"
  • Reaction Tube Height: 18"
  • Base Diameter: 7.75"
  • Water inlet and outlet size: 1/4" Polypropylene tubing
  • Method of feeding: Gravity or Pressure
  • Supplied Water Pump: Italian-Made Cobalt MJ400

Product Manuals & Documentation

Precision Marine Kalkreactor KR620

Owner's Manual available for download in Adobe PDF file format

Manufacturer Info

Precision Marine
For nearly a decade Precision Marine Systems has been the leader in the trade, creating top-performing, innovative components. Often imitated, but never equaled. Designers of the acclaimed Bullet Series line of foam fractionators, find out why public aquaria, custom installers and retailers alike choose Precision Marine Systems as their premier line of marine filtration.


Manufacturer`s Warranty: 1 year from date of purchase

14 Reviews



Experience Level: Intermediate


I spent a lot of time researching and this one was the best for my situation. Im supplying KW via a doser and the doser has a supply line in my top off container. This way I am not dependent on evaporation and can dial in how much I want to add. The unit isn't gravity fed so I don't have to worry about the down slope on the effluent line. This reactor works perfectly. Refilling is easy via the threaded opening and the drain tube is an option i wouldn't live without. I docked 1/2 star because I would have preferred a blue line pump but at least the cobalt is easy and inexpensive to repair & replace.

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JD from NY


Experience Level: Expert

Great value and quality

I have run this reactor for about 3 years now on two different SPS tanks. The construction is high quality and the design is generally very good. A word of caution regarding the mixing pump, as others have said the impellers will break at least once a year if not more, so buy a few extra. I run my mixer four times a day for 15 mins each mix. Four stars because of this design issue. One other piece of advice, I see the manufacturer and some users recommend or advise you to set this up with an ATO system by running your ATO line into the reactor and topping off with KW as your tank evaporates. Avoid a headache and just don't set your reactor up this way. One day you will come home and notice that your ATO stuck on and you have been dosing KW into your beautiful tank for the past eight hours and now all your coral are dead lol. Use a peristaltic pump and dose KW separately from your ATO. I do recommend this product.

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Experience Level: Intermediate

Great Product

This is the best designed Kalkreactor i have ever owned. Others are just too basic and fall apart. Quality!

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Experience Level: Expert

Precision Marine kalkreactor

This is my second Kalkreactor and by all means the best. I am using my Apex system as a timer for this reactor that turns on once a today and stirs the solution. My pH reading as a result of this reactor is at a steady 8.35. I truly believe that my corals are benefiting from the addition of adding kalkwassor. Set up is simple and the dispensing of kalkwassor into my sump is through my ATO system. I look at this system as one of my better buys .

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Experience Level: Intermediate

Works Great

This product works great. My only downfall as to why I rated it a little low was because the top screw will leak - even with the O ring provided. I has to threat it with plumbers tape and caulking on the top to prevent it from leaking. Ensure you have the pump stirrer on a timer as it cannot run continuously. Overall, very good product and worth the investment.... only downfall is me having to manually plug the top to prevent leaking.

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Experience Level: Intermediate

After 2 years Still love this!

These are built out of cell cast Acrylic. Dont be fooled by the other brands that are in its same price range.You will want to have extra impellers for the maxi Jet 400. Like anything they fail. I replace mine about each year when they break. Make sure you run the pump the least you can which is 4 15 min times each day. I would recommend buying a digital timer that can do 4 separate cycles. There is also a rubber O ring on top with a threaded cap. That O ring will also go out if your constantly adding kalk there. I would not even bother using that, and just open the main top, clean and refill. Hope this helps! Great unit!

10 out of 10 found this review helpful

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rayray from Los Angeles, CA


Experience Level: Intermediate

quality build, easy to refill

This is another well built & designed product from PM. I had to replace a 4-year old stirbar-type mixer. I feed 6 liters a day of RO/DI through a Litermeter III. After 2 months of use I can already tell I will have to replace the maxijet impeller within the year. But I guess they are cheap. Stirbar-types are indeed superior. Too bad they are twice as expensive. But, what limits most guys with kalkstirrers from using them is the constant need to refill kalk without making a powdery mess and loosing skin on teflon screws. This is the best part of the PM reactor is the top refill port, which I have to use bi-weekly. Using a funnel and some silicon on the seal, I have not had a single leak or spill.

2 out of 4 found this review helpful

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Experience Level: Intermediate

Pleased after several months.

I always review a product carefully. I have been using this kalkreactor for a few months now and I am very pleased with it's operation. Nicely made product and easy to use. I have the pump kick on and stir for 20 minutes 4 times a day & have it in line with my Tunze osmolator. This product will suit your kalk needs.

1 out of 1 found this review helpful

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SHANE from Morehead City, NC UNITED STATE


Experience Level: Expert


First,the quality of this product is #1. You definetly get your money's worth. Second, set up is easy. I bought an additional Tom's aqua lifter(dosing pump) and attached it to the out line from the reactor and from the dosing pump, ran a line to my refugium. On my reefkeeper elite system, I programmed it to stir 4 times a day for 15 minutes and to dose from the reactor if my ph falls below 8.4. Perfect thus far and has run flawlessly. If you dont have a reefkeeper or similar unit, I would highly suggest buying a timer for the reactor to have it stir 4 times a day for 15 minutes each cycle. As far as how much to dose, this reactor allows you to either dose the kalkwasser from the reactor by gravity or by dosing pump, so a little experimentation will be involved there until you dial in the correct drip rate or dose time. This is the third product I have purchased from Precision Marine and I havent yet been dissapointed. Good job Precision Marine.

2 out of 3 found this review helpful

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Experience Level: Intermediate

Easy way to add Kalkwasser

This is the second unit I have purchased. They are well-made, but over time I have had one develop a leak around where the stirring pump return pipe enters the tower. I fill it with 600 grams of KOH, and it will dose my 150 gallon soft and LPS coral setup for about 3 - 4 months. It is important to check the blades on the pump impeller periodically as they do wear down and/or break off over time. It's also easy to test the KW supply. Just unscrew the port in the top, and drop in a pH probe. If the pH is 12.1 or higher, all is well. Below 12, think about refilling the unit. Down around 11.6, and the KW supply is pretty much exhausted.

2 out of 2 found this review helpful

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