If your going you might want to check out these..
Advanced Aquatics in Schuamburg is a pretty nice store that has tons of supplies and has a good selection of livestock. If I remember right there is another store on S. Roselle rd also that is fair.
Advanced Aquatics (Glen) -- 879 S. Roselle, Schaumburg 60193
847-882-5747
Living Sea Aquarium is in Park Ridge right next to Ohare. They have the largest selection of fish I have ever seen. Large Angels to Anglers.. They also have a couple large tanks with some stingrays and misc fish.
Living Sea Aquarium (Mike) -- 811 W. Devon, Park Ridge 60068
847-698-SALT (7258)
Reef Dweller is in the N. part of Chicago and can be a little tricky to find, his store does not stand out from the street so you have to watch close. He doesn't have much for fish but he is the man in the area of sps. He has about 3-4 large rubbermaid stock tanks that have frags. He knows his sps! One thing is you might want to do is check out his website and look at the coral on it, I'm not sure how up to date it is but most of those and his real "nice" peices are actually at his house so you need to give him a heads up so you could actually get them when your there. I found that out the first time I went there, he had lots in his store but the ones I wanted were in his home tank.
Reef Dweller (Menard) -- 6023 N. Lincoln Ave., Chicago 60659
773-743-5574
One other store that I never got the chance to visit was Splash of Life, last I knew it was in Elgin. Not sure if it's around anymore and there website doesn't work but I heard they were a very nice store too.
Hope this helps your trip and have fun! Ryan
