The aquarist setting up a reef aquarium system by individually purchasing all the various hardware devices has a lot to do, particularly if it is a first system. There are so many questions to be answered, and so much research to be done.
The danger with a system put together by the aquarist is that one or more of the devices to be used may be below par. If the research is inadequate in any way, or if the aquarist has been surprised by the cost of some devices, aquarium equipment may not be up to the job or corners may have been cut to save money. Any actions such as these are likely to lead to problems.