Dude.
Please please please do not purchase that animal. I work with Nautiluses at a university, where we have a 280 gallon tank and all the resources of an institutional aquarium to keep them. Even here, they are very difficult to keep, and definitely not for beginners. Forgive me for sounding rather harsh, but if you are thinking of getting a nautilus the same way you thought about getting your octopus (as per the discussion in the 'Introduce Yourself' forum), that animal will die within days, even with water changes. Do you have space for a 100 gallon tank?
If you took your vulgaris back to the store (as many seemed to have advised) and are looking for something to use the store credit on, buy some live rock to get your existing tank circulating. A nautilus in a LFS is pretty much doomed to death anyway, please don't take it home just so it can die after even more stress. If the store can't sell it, maybe they won't get another one. Nautilus are vulnerable to over-collection, and the pet trade is not where they should be ending up.
I'm sorry if I've read your intentions incorrectly, but you seem very inexperienced at keeping cephalopods, and not particularly willing to take advice from the large number of real experts on this forum who've offered it with regard to your recent octopus purchase. I hope you stick around and learn from the information available here. I'm not trying to attack you for wanting to learn - I am happy to chat to you more in a PM about nautiluses if you really want to set up a tank to keep them.