I kept marine's for years, if you go down the do-it yourself route { i.e building your own set up} get the biggest tank you can and go the undergravel bio filter route, it takes a while to mature the bacteria but once its there evrything runs pretty smoothly, there are also ready made marine aquariums available these days too, they are really easy to keep on top of and i'm thinking about getting one, there expensive but the simplicity of keeping them soon makes up for it in comparison to DIY jobs, a friend of mine has one and he has the clowns having babies now
......also think very hard about what you want to keep, some fish are really nice and quite hardy little buggers and will take a fair amount of imperfections in the water, others can be extremely sensitive and will drop dead at the slightest imperfection in your water, also bare in mind the expense, EVERYTHING for marine tanks seems to cost a small fortune, especially the fish and also the salt you'll need, and you need flamin TONS of the stuff !
If i was going to do it again i would get little clowns and a few anenamones, keep it simple sort of thing.
When i had my last tank i had a really nice set up all built into the chimney brest it cost me about £1500 in total, i then made a huge mistake (unbeknownst to me at the time) in buying this little puffer fish that grew and grew, its teeth grew and grew too, then it started devouring everything in the tank i used to watch it chewing on the rocks even, eventually it was the only thing left in the whole tank and by this time it was about a foot long and its teeth where bigger than mine...i fed it one day its usual frozen shell fish and it came to the surface for it's feed and proceeded to take the end of my finger off ! 8 stiches later it then went back to the fish shop !!
and said tank and set up was flogged for about 300 quid if i remember correctly. so if you do get one keep away from predator fish.
