Advice/input on a new tank: considering seahorses

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I have a 33 gallon tank which is empty. It was a plant tank so it has an Eheim filter, 90 watt of flourescent lighting, and a calcium carbonate substrate about 2 to 5 mm size.

I was considering setting up a Seahorse tank. If I did this I would get lots of macroalgae growing in the tank.

My other option would be to make it a fish only tank for interesting non-reef-safe fish.

Just wondering which option will be most rewarding and enjoyable, or give me the best return on my effort.

If I went with Seahorses, the questions I have are: how hard is it to get ahold of captive-bred seahorses in Vancouver? And which species would be best for that size of tank?

If I went with a fish-only tank, any advice on a good mix of fish get?

Not sure what I want to do with this tank yet, it is just sitting there empty so I want to do something with it.