thanks Mickey, but what I do when I want to suspend a rope away from the tank sides and don't have anything above to suction cup it to, is to use acrylic rods similar to the 5/8" square rod shown in this photo. I'm using it here to suspend my 24" Orbit over my 30" open top tank. It looks classy and does not block any of the light. The only downside is if you have climbers like crabs, you are only making it easier for them to escape. when you cut the rod with a hacksaw to fit, always bevel it slightly and measure an extra 1/16" longer than the gap you wish to span. that way the rod will fit snug and tight in your tank frame, and won't shift around even when it bends under weight.
here are some examples where you can get cut acrylic rod on the web, but
I prefer to buy scraps long enough for my tank at a local plastic goods store.
I wish I could grow Subwassertang better as that "freshwater kelp forest" motif was actually what I was going for. I'm curious to see if the S-tang will continue to grow denser, or grow further away from the rope, since further away would really give the kelp forest effect I'd be looking for. I recommend anyone who's S-tang grows emerald green and pearling in their tank, to go ahead and try this rope idea, as it will look glorious!
Storm - technically I could take an existing grown in rope and simply shove the aluminum wire inside thus having an already grown out form, however the growing patterns toward my light source would not look as authentic as had I started from scratch.