Testing your water
Many of the fish and corals that we keep in our aquariums can be more sensitive to water conditions when compared with most fresh water fish. This is even more critical in smaller set-ups as problems with water quality can get very bad very fast. You need to be testing the basic parameters in the beginning while your tank matures. Once you get a lot of coralline developing and you have started adding more fish and/or corals which consuming many elements from the water, you will need to slightly expand this to include other elements.
Without testing your water quality at least weekly, you will not be able to determine how well your set-up is maturing or much much elements the system is consuming from the water.
The below link will allow you to better understand what I am talking about