Actually commercial posts are strictly forbidden. I understand wanting to get your forum going, but I don't know you, and I hate to think you would do it on our hard work. Put in the time, get a few members and continue posting even if your posting to know one, your forum will take off on it's own...maybe, I personally don't like forums connected to a retail establishment, idea seems OK, but I just don't like them, hopefully for you there are plenty of people that do not feel the same as me.
You want people to join your forum? Post here helping hobbyests with their aquarium problems, post a link to your site in your sig, that does a whole hell of alot more for your site than posts such as these