CaribSea ARM Reactor Media - Extra Coarse

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CaribSea ARM Reactor Media - Extra Coarse

100% Recommend this to a friend (8 of 8)

SKU: 204105

reg. $22.99

Special Price: $19.54

In Stock: 66
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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.


8 Items

  • Great product!!! By Reefinman on 11/18/2015

    This is the first time using the coarse media and I'd say it works great.
  • not sold in bulk by bulkreefsupply By trueopinion on 12/9/2014

    I can't believe BRS doesn't sell this in 50 lbs. Why are they just keeping it in 1 gallon containers? Bulkreefsupply should sell this in bulk (like its name) and not in 1 gallon container and bits and pieces. Would give 5 stars if they sold in 50 lbs bulk. It's cheaper that way and people will buy for sure. Now I'm looking somewhere else where they sell it in 50 lbs
  • The Best media you can use in a Ca Reactor By Mohamed on 10/25/2014

    I have been using ARM Extra Coarse in my GEO 618 reactor for over a year and Alkalinity, Calcium, Strontium and Potassium are spot on. Am running my reactor @ 6.4 PH and even tried 6.3, the media can really take it without turning to mush additionally for the past year I haven’t lost more than %15 or %20 of total volume used in the reactor.
  • Alternative Use By David on 10/5/2013

    I don't use for Caclium Reactor.

    I have found this sized is better than crushed coral or rubble rock for propagating and attaching mushrooms and loose zoanthids.

  • Make sure you rinse By WetDreams on 8/18/2012

    It says ready to go pre rinsed so I did not worry about it and I lost a few ricordia other than that its a gret product.
  • excellent By Chu on 1/19/2011

    I have reservation when buying this because of the size. However, after watching it dissolve just as good if not better then the smaller types of media it got me convinced. I will buy this product again.
  • A definite buy By Jeffrey on 12/25/2010

    I have used the smaller media and prefer the larger. This product doesnt melt and goto mush like the fine media will. Good ph of 6.5 all in all no complaints.
  • larger size makes a difference! By Jeffrey on 10/17/2010

    Tried many brands and sources, need to stay away from small particule sizes on larger reactors to avoid clogging. This one works great and glad BRS carries it as it seems to be harder to find.


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Product Questions

Is the media sold by the pound? What size is your containers?
Question by: mario on Nov 25, 2013 5:43:00 PM
Hey Mario,
Its sold by the container. The weight of each container is a little different depending on the size media you purchase but they are all right around 1 gallon.
Answer by: Bulk Reef Supply on Nov 25, 2013 5:43:00 PM