If it's the stuff I am thinking of, I used it to seal a leaking shower, it didn't work very well, and it stunk, the vapour given off from it would worry me, as it lasted for about 5 days, so I would be wary if you need to put something in the enclosure soon.
I would always recommend a Aquarium sealent, you are guaranteed that it won't harm your animals as it is designed for use in fish tanks and fish are more susceptible to things.
You can buy it from most Aquatic centres.
Neil
