Easy to maintain "stuff"

[crossxfire2]

In the next 9 months I will be shipped off to college. Where I am going, I will not be able to keep an aquarium. Despite that fact, I am still determined to stay in the hobby.
While attending college, I will be able to visit my house at a maximum of every 3 weeks. So, maybe I still have a chance at keeping SOMETHING at my house. I have a few ideas, and a few questions. Here they are:
I know I wont be able to keep fish, so, is there a coral/polyp/mushroom available that would thrive, even if I were to tend to it once every 3 weeks?
By this time I will have to use an auto-top off mechanism because my water evaporation is great. While I'm at it:
For yall that use these systems, may I read your opinion on them? I've herd that the ball can get stuck, consequently overflowing the aquarium.

Thank you!

-Van

[txstateunivreefer]

get a tunze osmo i have bought built and none of the top offs i have used in the past were as good as the osmolater

[crossxfire2]

ok, thanks for the input!