I have that same tank...
I have that same tank...
I too used mine previously for geckos (fan-footed geckos...) and freshwater angelfish before that, but it started out as my first seahorse tank when I was in grad school, and I have had it up as a reef for about 2 years now. I think it is nice because it is different, with the biggest challenge being 'scaping it.
Back when I used it for seahorses, I used very little live rock, but had lots of long plastic grasses and some long/ thin driftwood. I do not have any pictures from back then, but here are a few from the last 2 years. It was made by All-Glass Aquariums, and was their 15XH - too bad it is not made any longer...
I think it would be great for a couple of smaller seahorses - good luck!