If you enrich your brine that would be better but if you decide to try seahorses try and get some that are already feeding on frozen mysis shrimp! deuce Seahorses in such a large tank would be a bad idea, first because in such a large tank seahorses would be extremly hard to feed, second because the need for circulation in a reef tank is great and seahorses are poor swimmers they would probably, if your reef would have circulation like mine, get blown around, lastly seahorses need hitching posts and in a reef tank they would likely hitch on to corals and gorgonians which wouldd be harmful for the inverts!