20 gallon long for paired Brazillian seahorses

Here is my setup...

20 gallon long tank
330 bio wheel filter
over the tank skimmer
live rocks
some corals
hard corals.

Can you think of anythinkg else? Or will I need a bigger tank? Please advise

 

I wouldn't put corals in with seahorses at all. Also, a breeding pair of horses would do better in a 20 gallon high than a 20 gallon long as they need to swim high up in the water column to feel comfortable enough to breed. You'll also need to provide the horses with hitching posts (of the non-coral variety) so look into adding some plastic plants which you can use forever or until you have a chance to grow macro algae in the tank for them to hitch on. When you consider a sea horses feeding requirements, your filtration choices will not be enough to keep up with the bio-load that their feeding can produce. If by over the tank skimmer, the only one that I know if is the Prizm which is not a good skimmer at all so keep that in mind when you're out shopping for a hang on skimmer.

 

I agree with everything amcarrig says. I used to keep sea horses and they need a tall tank to be happy. A 29g is a perfect tank for them. They also need to be feed 3 times daily as they have no stomach to speak of.
Live corals can also injure them. I used to use dead branching coral and plastic plants.
They also prefer slowly moving water. The 330 penguin may be too much flow for a 20g. I would go with a penguin 200 and a good HOT skimmer like the remora or bak pak.
Good luck!