Memorial day is 05/25/2015 – Orders will ship out on May 26th. There will not be any deliveries or shipping on Monday. Any order placed after 11am ET on Friday May 22nd will not start to ship out until Tuesday May 26th.
I know some customers have purchased them for that purpose, but I haven't heard any feedback. The tip sheath is stainless, but as you probably know - that alone is not a guarantee of survival in salt water. I'd consider passivating it before deploying in a marine aquarium: http://www.howtobrew.com/appendices/appendixB-1.html