actually, that what used to be recommended, now many of us have reduced that by 2* wildcaught or not!!! and 82 is outta the question. Many horses have shorter lifespans in tanks kept above 76* which is the top of what many here recommend. and its HIGHLLY recommended to get captive bred horses-yours are coming from OR, right? well, to be honest: its kinda a marketing ploy. They tell ya one thing, and when you start having problems, they'll tell ya to reduce temps.
anyway, alot of corals ARE ok with seahorses. zoanthids, shrooms, leathers, actually: alot of softies. I wouldn't do lps because of the sweeper tentacles, or sps because they would hitch on the sps and the flow needs of sps it alot more than what horses need/like
if you WANT to try actual grass, it grows slow, but the sandbed needs to be 4 inches... which seriously cuts down on height in a tank.