I kept marine's for almost 10 years culminating in a 1000 litre mainly SPS system with inline frag setup (coral propagation if you're not familiar with the term frag). What is it you want to know?
Marine tanks are spectacular but they require a lot of work and money if you're going to so it properly. Main challenges are;
-You must use RO water and then pre mix and pre heat water change water
-You're gambling with your aquarium livestock (fish) if you don't have a quarantine system (marine fish can carry and introduce whitespot or worse marine velvet, the treatments of which harm corals, so once the disease is in your tank you have a problem
-The aquarium needs to be a stable temp (corals haven't really evolved to take temp swings) but usually the issue is actually keeping the tank from getting too hot in the summer as the amount of kit produces excess heat (I ran a chiller on my system to combat this)
-Testing - you need to do a lot
-Bigger the tank the better. This allows for more stable water parameters
I'll leave it there for now but don't take the leap lightly. And don't do it on the cheap. You really want an aquarium with a sump system, anything else and it's not as easy. Some will disagree in parts with some of my points but in the main they are correct. I do miss my reef tank but it was a ball and chain in terms of ongoing care and maintenance and it cost alot to run.... circa £300 per month (and that's before buying new stock). It was big system though
A good forum if you want to start investigating more is Ultimate Reef
Where are you diving by the way? I'm a diver myself. Me getting into marine's led me to want to do that and I've done a fair bit since (Uk, Egypt, Maldives, Thailand)
