I know this is a late addition to this post but I was out of town. Or, rather in your area. I frequently go down to Fripp Island (which is where I spent the last week). I have found a link to several artificial reefs that the SC DNR maintains. You can find these at the DNR website. (The webmaster will not allow me to post the URL. If you contact me I will give it to you).
I have not dived on these sites extensively as a matter of fact I have only been on Fripp Island Reef once, 7/15/09. Therefore, I can't present myself as an expert in the Fripp Island area. What I did find last wednesday was similar to what Lives4sharks describes: low vilibility and good current. Fripp Island reef depth is about 50'; visibility was 8-10' last wednesday. We were unable to get an anchor to hold, so coming up the anchor chain may not be an option on a given day. (On that dive I actually found three anchors that others had cut free) So, from that one experience I would put it in the advanced category. However, once you feel comfortable with your buoyancy and low visibility experience, I'd be glad to hook up with you and try some of these sites. And to Lives4sharks, I've been told by multiple people that there are sharks in the St. Helena Sound. I've heard people talk about shark fishing in the sound and off Edisto Beach. Another diver toldme that they ran into tiger sharks on artificial reef 6HI off of Hunting Island, SC. I was told that the sharks were not acting agressive, but I respect the diver and his advice. If you're interested in these sites let me know, I would like to find others who are interested in diving near the Fripp Island area.