Adam, I asked the question without mentioning that I have a large cluster hanging out in the back of my 55 that I put in when I first set it up as a FO. Mostly because I was afraid of that they might be problematic. It seems to be slowly dissolving, so I guess whatever it contains has been leaching into my system for the duration of it's existence. although I haven't noticed any specific ill effects I will say that I haven't had great growth in species that I have seen prosper under similar conditions as mine. but then maybe I'm just looking too hard for a scapegoat instead of buying the MH's I've been putting off. The shells do have considerable coraline growth and provide a good hide out for my smaller damsels, would you remove them in my position?

Mark, that has to be the most simple, brilliant thing I've heard in a long time... cheerios... sheer genius... seriously I'm kinda dumbstruck,it didn't even occur to me but it's perfect.... the dry ice thing might work because freezing doesn't adversely effect early set in cement, it just continues it's cure once thawed, but who wants to buy and handle dry Ice over Cheerios. You can't snack on dry ice while you work. I'm gonna try that this weekend, I've been wanting to make some aragocrete for some time, I even have the setup and materials (no oyster shell), but have always been bothered by the porosity issue.

I really can't equate how valuable this forum is. All kinds of positive and negative exchange and the ability to pick the brains of some highly experienced, helpful people. I've praised it before but I like to encourage things that benefit me so keep posting everybody and thanks 

I don't know.  I wouldn't try them, just to be safe, but I don't think anyone has really tried them out.

Adam

As I mentioned in another post... Oyster Shells are bad.... very very bad.

Adam

chrisslc wrote: Hey fuzzy, as for how to create pourousness (sp.?) in the aragocrete, the traditional way to "air-entrain" concrete is to use one of many admixtures for the purpose. But, most of these are detergent based and would pose a threat to a reef of course. you could try mixing in crushed ice at the last moment but the additional water from melting and the cold may effect the setting of the cement directly in contact with the ice. you could possibly grind up parafin wax, mix it in, then boil it out once the cement is set. I wouldn't think leftover wax would be a problem for the tank. I only pose these ideas because it sounds like you're willing to experiment a bit and I'd love to see if it is possible. It would go a long way towards convincing me to use aragocrete before natural rock.

Hey, thanks for the suggestions I will definitely try both.  (am already planning dry ice shavings for the ice because it lasts longer and evaporates without screwing the mix up) This is the prime reason for my new tank... to experiementing with the agro.  I already worked out a deal with my local plastics provider to give me all of the plastic shavings I need.... also worked out a deal with a local seafood store to allow me to pick up as many oyster shells as I want...  and I live near the ocean and am going to try some natural substrate for my mix.   It's going to be a slow process because I am documenting it and following a very controlled research process.  The goal is to have hard fast proof in the end even if it only proves a little.

-Fuzzy Weasel

According to page #138 of Sprung's Invertebrates:

Filogranella species

"Members of these genera form small calcareous tubes 1mm or less and have red or white crowns. They reproduce in aquaria, and can be found on and inside pumps and plumbing, as well as on the undersides of live rock or on the walls of the aquarium or sump. Thick colonies of them sometimes occur on reefs, and they are occasionally harvested from the Caribbean.

Filogranella sp. from the Bahamas. These form calcareous tubes and survive and reproduce in aquariums. They should be maintained in the shade to prevent algae from smothering them, and they prefer moderate laminar water flow."