Everyone wants everything now. Blame it on commercialism, but it does make aquarium care much more difficult. Many a sad tale started with the comment "all my fish died" followed up by "I just set up my aquarium 4 days ago".
Sometimes the question you do not ask is the most important question. I was a clerk working in my first Aquarium store when I was approached by a young hobbyist interested in one of the Percula Clownfish we had for sale. He asked me if it was a true Percula or an Ocellaris Clown and I pointed out that this was a true Percula.
I was cleaning my 55 gallon freshwater fish aquarium yesterday and placed a new Aqueon 55 power filter on the tank to collect some of the algae debris floating all around the tank. I noticed about 1/2 an hour later that the filter cartridges were already clogging! (OK, there was a LOT of algae before I cleaned.)
The most difficult time in the life of an aquarium set-up is the initial phase, as the hobbyist waits on the system to cycle. Until this occurs, any fish in the aquarium are at risk to exposure to high levels of ammonia and/or nitrite that can reach toxic levels, killing the fish.
Understanding the standard water parameters for a marine aquarium and how they can change in the aquarium will provide a great step in maintaining a healthy environment for the aquarium inhabitants. Knowledge of what to test for and how to correct conditions when readings are out of their natural range will be essential for success.
Don Roberts