Psyire :
i got the media from fins reef but there is a better deal in aquarium specialty for $100 you get 5kg of media . here it's the link maybe fins reef have the same deal but i didn't saw it in the website :
http://www.aquariumspecialty.com/cat...ee33326c128714
IMO you need at least 3 kg and if you can even to put in your reactor 5 kg it will be better (the reactor will handle easyer on the nitrate)
xinumaster :
again both media will work (the carib sea cost about $20 for 1 kg)
but the problem it's the density when the media look more like sandwich the density higher and when it's start to melt the flow thru it hard and the drip not steady you need all the time to adjust the drip and the reactor not work properly..
more then that for big tank like your , you need full media in one reactor if you want good result (no less then 3KG ) and even you mix the media again when it will start to work the media will melt and clog again.
i don't know if you have reactor but you can make one big from R/O housing and mod it as a reactor . also if you have good calc reactor (big one) then you don't need a second one for the arm media unless your calc reactor can't keep the ALK in the tank steady (the sulphur media will reduce most the alk in the tank )