The thing you want to remember about seahorses is that they are very slow and methodical eaters. I have heard someone kept a bangaii with their horses and hasn't had a problem. The clowns may out compete them. I'm sure others will give you more advice than I am able to as I just started keeping...
Bought ANOTHER tank(20 gallon long), some PC lighting, a picasso trigger to go in one of our other tanks, a porcupine puffer to go in another of our tanks.
Oh, and some beer to drink while we set up the 20 long!