(2 customer reviews)


The CR612 calcium reactor will hold 8 pounds of large grain media and is well suited for reef aquariums up to 200 gallons.



SKU: CR612 Category: Tags: , , , Product ID: 1731



  • 6″ diameter reaction chamber
  • All cell cast acrylic construction
  • Key hole slot for lid removal
  • Full access to the reaction chamber
  • Micro ball valve effluent control
  • Sicce Syncra 1.5 pump, bolted to base plate
  • pH probe port in lid
  • pH probe adapter included
  • Auto fill bubble counter
  • 11 x 10 foot print, 16″ overall height
  • Comes with tubing harness shown in picture
  • All tubing fittings are 1/4″ OD push to connect

Additional information

Check Valve

None, Add High Grade Check Valve for 19.99

Precision Needle Valve

None, Add Precision Needle Valve for 25.99

2 reviews for GEO CR612 Calcium Reactor

  1. David Bourassa (verified owner)

    This is, by far, the most beautiful reactor I have seen or utilized in this hobby. Every detail is sleek, modern and well thought out. I have and love an older 612 model and I was not sure how I would like the new white version in person but once unpacking I instantly fell in love. The pump plate, black silicone and color coded tubing are just a few highlights that you don’t see in other reactors. The uniseal vs older threaded elbow is a plus and even the etched GEO is etched in this reactors lid stand out in a top shelf kind of way. There is only one name in the game for Calcium Reactors and thats GEO hands down. I’m as stoked to show this off as I am colonies of Acros. Now I am looking at the rest of their range to see what will be under my stand. Fantastic job GEO.

  2. Freddie (verified owner)

    When growing up GEO always comes to mind for Calcium Reactors.
    Last fall I was ready to migrate over to one and reached out to GEO.
    GEO took down all my specs and we went with the CR612 for the main reactor and the SMC415 for the second stage.
    Running the large Reborn media with 10% of ZEOmag in stage 1 and the small ARM media in stage 2.

    Not only is this the most beautiful setup, but my SPS are growing more too, from the constant alk.

    Thank you so much for taking the time and bringing the system together for a smooth transition.

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