You have to remember that in keeping a saltwater tank, you are attempting to re-create a situation that does not occur in nature...a closed system.
Cycling, the period of time (3-6 months) that it takes for the enclosed container to stabilize the water quality, is the most necessary, and often most overlooked, part of the hobby.
Patience is required to maintain a healthy tank.
No, unfortunately. And this is where I differ with so many people on the keeping of animals in captivity.
There is absolutely no way to keep the same water parameters as are found in the ocean, in an enclosed tank. No matter what you do, how much you filter, and how many water changes you do per month ( I do two 10% on the tanks per 30 days)...it is still a cesspool compared with the sea.
Make sure you have the financial sources to obtain new saltwater, a series of very good filters and a skimmer running nonstop, and clean them religiously...then, you can at least keep the tank as fresh as a tidepool, though you don't refill it every night !