Thanks guys. I think I ll give it a shoot, sounds like it will be ok.
This anchor is 8 lbs and about 7x7x7 inches. It will fit nicely in my 90 gallon. The idea is to attach a rope covered in moss to the anchor and set the anchor next to a large tree stump. The sand will be littered with some black river stones and a few broken terra cotta pots. Ill post up a few pics when I get done.