Well, I will be the one to come in here and say no skimmer. I kept seahorses for 3 years, in several different size tanks (20, 46, and finally a 30). I only ever kept at maximum 3, which was in the 46. I think 6 ponies in a 46 would be a heavy load on the tank.
I had only a eheim canister filter running on the tank, and a few snails as cleanup. (Hermit crabs are generally not a good idea with seahorses). I had lots of macro algae for nutrient and nitrate export, and did regular water changes on the tank.
As for feeding they got fed once a day in a food dish, sometimes they would eat all at once and sometimes they would leave some and come back later. They were trained on the dish, that way they ate ALL the food I put in the tank, and there was no waste.
Flow in the tank was kept to an absolute minimum. The main reason for my choice not to use a skimmer is the havoc micro bubbles can cause on a male's pouch. They manage to get in there and then you have to be doing pouch evacs. I never once had a male with pouch problems, even with giving birth every two weeks for countless years.
So, success without a skimmer. But I had lots of macro algae. And they consumed all food put in the tank.
-Diana