will look great when you get everything going, i love long tanks.
as for the new livestock, i would hold off on the goby and blenny as they need a lil more established tank to strive as does the cowrie (or you can feed him lettuce like marc does)
for good sand movement and mixing a dragon wrasse works wonders especially for your thin sand bed (make ure you have finished the full cycle of course)
id say to just keep addin some more crabbies and snails slowly, maybe not anymore for a little while so the tank has time to establish an dyou get a fish or two
as for the new livestock, i would hold off on the goby and blenny as they need a lil more established tank to strive as does the cowrie (or you can feed him lettuce like marc does)
for good sand movement and mixing a dragon wrasse works wonders especially for your thin sand bed (make ure you have finished the full cycle of course)
id say to just keep addin some more crabbies and snails slowly, maybe not anymore for a little while so the tank has time to establish an dyou get a fish or two