CaribSea ARM Reactor Media - Coarse

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CaribSea ARM Reactor Media - Coarse

100% Recommend this to a friend (6 of 6)

SKU: 204104
In Stock: 81
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Quick Overview

ARM Coarse Reactor Media contains calcium, carbonate, and trace elements.

  • Nearly 50x the Strontium of other brands (7390ppm)

  • Precision grading allows for maximum carbon dioxide penetration

  • No gastropod shells means the lowest phosphate content (less than 1/10th of 1ppm)

  • Highest solubility of any reactor media (metastable at 8.2)


Full Details

One of the most trusted media for calcium reactors in the industry. The media is a complete solution which includes both calcium and carbonate as well as essential trace elements.


The media comes in three forms Small, Coarse and Extra Coarse.


  • Small – Provides the most surface area which maximizes the amount of calcium and carbonate which can be added to the tank. *The small size can clog many reactors and may require on-going maintenance.
  • Coarse – larger size granules which are less likely to clog equipment.
  • Extra Coarse – Largest size granules and the least likely to clog equipment which results in the lowest maintenance option.


Note: All ARM media is packaged by volume in a 1 gallon container. Weights may vary from container to container.


6 Items

  • Good stuff By Jim on 6/27/2014

    Great size for reactor flow and nice that product is clean and ready to use. If the assays are to be believed then good quality material and nice there's actually magnesium in the blend.
  • I simply love this product!! I have been using it for years!! Its the best on the market... and my Acros love it too!! Best thing you offer it at a really fair price!!! By ndesquise on 5/13/2013

    Tried other reactor media!! My rare corals love this the best!!!
  • Great By Tj on 3/18/2013

    Love it great stuff
  • Great Product By Lindsey on 7/12/2012

    First time using this product but I love the size of the chunks and it works very well in my reactor. this is an 8lb tub. It took me 12lbs to fill my MRC-CR5. the courseness ensures that your recirc pump in your reactor can have a good flow around the media so it dissolves evenly
  • Staple of the Reactor By Mark on 4/25/2012

    I've used this for years in my CA reactors. Never had any problems.
  • love it By cynthia on 12/5/2010

    quick and easy to clean, also works great in my cal reactor.


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Product Questions

What is the rough average size for the coarse and extra coarse media?
Question by: Matthew Stachler on Oct 8, 2017 8:40:00 PM
Hey there,
Thanks for getting in touch with us in regards to sizing for these medias. The coarse media I measured was about 0.25-.5" with more on the .5" end. For the extra coarse, I measured them at 1-1.5" with more on the 1" side. Please let me know if there is anything else that we can assist with. Thanks!
Answer by: Tyler Schafer (Admin) on Oct 15, 2017 10:05:00 AM
I could not find the weight of this product. What amount of media comes in the container?

Thanks Glenn
Question by: Glenn Relethford on Nov 27, 2015 3:33:00 PM
Great question!
This will weight 8 lbs. Feel free to let us know if you have any further questions!
Answer by: Connor (Admin) on Nov 29, 2015 10:23:00 AM
About what volume in liters is This? I have a dual chamber reactor and require about 11-12 liters of media.
Thank you, Mike
Question by: Mike cline on Feb 16, 2017 12:26:00 PM
Hey there,
Caribsea ARM media is sold by volume and comes in 1 gallon containers, which would convert to a bit less than 4 liters.

Have a great day!
Answer by: Zack (Admin) on Feb 17, 2017 3:32:00 PM