Substrate

[2639]

Is crushed oyster shells bought from a feed store a good substrate? I bought a bag thinking I was gonna make some artificial live rock but won't now. I need to do something with the crushed oyster shells.

[Doctor_Reef]

Take it back!!!! :)

[2639]

LOL I take it take it that's not good eh?

[Doctor_Reef]

Yep!!! Not for a reef tank...You really need fine sand....for the critters... :) That type substrate would give lots of places for debris to lodge and cause you problems....

Crushed oyster shells are also very high in Phosphates. At the pH of a normal reef tank, they won't de-adsorb chemically. Unfortunately, they will end up in the tank biologically. Bacteria don't have mouths and create enzymes that dissolve the P from the shells. Basically, it's only a matter of time before they are removed from the shells.

[MikeS]

Agreed with Curt....you can vaccum out larger substrates, and with adequate water flow above the substrate, detritus buildup can be managed...however with oyster shell, the primary problem is the high level of phosphate.

Aragonite itself will also have phosphates...but not to the degree shells will. (another reason BTW that empty shells don't make good decorations...)

A good aragonite choice for any application (DSB to SSB) is Caribsea'sSeafloor special grade reef sand...it's 1-2mm in diameter...so you can have decent flow over it without disturbing it, it's coarse enough to vaccum it (in an SSB only, of course) but fine enough to be used in a DSB if you so choose....

Mike

[2639]

Interesting mike. What is the recommended depth for a sump/refufium? dsb or ssb?

[MikeS]

In a sump/fuge, actually, I would not recommend a substrate at all. Remote DSB's don't tend to work well, there is no real reason to have a substrate in a fuge/sump, as it will simply increase the rate of nitrate production in the system as a whole. ( remote plenum/sandbed systems are viable, but unrealistic for the average reefkeeper because of the size required to be effective...)

Substrate choice for the main tank can be a difficult one, and a hotly debated one as well...there are many different options out there, all with positives and negatives. Let's start with your long term goals for your tank and work in that direction...then we can hopefully help you select a substrate that will best fit these goals...

Mike