Hi Craig,
Well, I'm not really sure about whether it can be blamed for the cloudiness. I've read where some people who were using it experienced cloudiness, but it is unclear whether the two events were coincidental. Conclusions are often irrational and since I've never used it I can't really say.
One thing's for sure, you don't really need it so if it's in a bag, and is easy to handle, then definitely take it out to see if that helps. If it's under the gravel though then forget about it and just worry about one problem at a time. I would much rather you concentrate on getting your plants to regain their leaves. That objective is 1000X more important that cloudiness, and probably, by the time you sort that problem out, I'll bet the cloudiness will have cleared a little. You cannot rush a tank that size.
Cheers,