What can I keep in a 6g tank?

I am an experienced reefer. I just am eager to set up another nano.

I want to make a more lenient care tank. I don't want to do 'weekly' changes, but I'll do every 3 or so. I plan on keeping macro algaes and live rock. Maybe some softies, and tube worms.

My main question is, can I keep a dwarf seahorse in a 6g? I'm not going to try if it's out-ruled. But is there any creature besides a shrimp?

Thanks, WHEATIESSSS