Your tank is not suited for seahorses.

Your powerheads are not compatible, your fish are not compatible and some of your corals are not compatible.

Sorry.

For more info on seahorse safe fish and corals, look around for a guide entitled What's safe, What's not? It's in the seahorse.org library and has been updated recently. Apparently I can not post a link until I make a few more posts.

For flow you can have a descent amount of flow in with seahorses, but it needs to be broken up so there is no area of intense current, and a place of retreat from the current. Powerheads like Koralia's aren't good as the gaps in the design allow for the tail to get trapped in it. Seio's are a bit better if you use the fish guard. I have tried a 620 never an 1100. I would be concerned if they were on controllers though.

HTH