freshwater dip to evict unwanted hitchhikers?

[newfound77951]

I've heard this referred to a few times.....but not sure if I want to do it. My measly 20 lbs of live rock is infested with predatory crabs. I've removed 3 (they were dead, not sure if they're being killed by the others) and there are at least 3 more plus one very loud pistol or mantis shrimp. Before I add any fish to this tank I need to get these crabs out. Ive heard that a FW dip will do the trick but I want to make sure I'm not going to damage the rest of the LR too badly, and also how long I would need to keep the rock in there. Or, for that matter, is there a better way???

 

[lando]

I would try a hyper-salinity dip instead. Dip it in water with a SG of 1.030 or more. Have a bucket of normal, aged SW right next to it so you can rescue any wanted hikers.

I've removed 3 (they were dead, not sure if they're being killed by the others)

Are you sure they are not molts? I have been fooled by that before.

 

[roka64]

I agree with Lando, go with the hypersalinity. If I remember correctly, your tank is still cycling, of so, that may be the cause of the deaths, if not Lando is probably right, they could be molts. My big hermit crab's molt looks EXactly like him, it is not faded or see through, like a shrimp's molt.

 

[angelscrx]

A FW dip is not truly FW. It is a hyposalinity dip with maybe salinity as low as 1.10 but I would go with the Hypersalinity as recommended. If that doesn't work try pouring carbonated over the rocks.