Hey Brad,
Cyano is not fun to deal with but it is manageable so don't give up. You started dosing Vinegar not too long ago and that is changing the bacteria count in your system. I believe, don't quote me, but my past experience is that cyano comes in when the bacteria count get out of whack. Once your system gets back in "check" I bet it will go away. For instance, when my fuge light burnt out and the chaeto quit growing, I noticed more brown algae on the glass of my DT. Once I got a new bulb over the fuge, about a week later cyano started to show up. I aggressively sucked out the cyano for a week or so and after that the balance came back and now it's gone. I didn't have a ton of it, but it did show up in low flow areas and actually started to grow over the top of the chaeto as well and probably would have choked it out but I didn't allow it to by pruning the chaeto pieces with it on it.
Hope this helps. Other than that, I like the 2 islands idea as well but you just changed your scape. Post up some more photos of the structure and maybe we can chime in more. Maybe a side shot through the tank??
op2:
