... trade the cannister filter in for it.

... cannister filters are not really a good choice for a reef
tank,

Thanks for the feedback guys, but I am not sure I understand. From the
reading we have done and from conversations with dealers, we were led
to believe that a biological filter was required to convert Amonia to
Nitrite then Nitrite to Nitrate, with the latter being much less
harmful and cleared out through water changes. The dealer who sold us
the tank also sold us the 204 on the basis that we needed more
biological filtration capacity than the Juwel 240 integral filter
provided (which is apparently rated for fresh water tropicals only).
The feedback here seems to suggest that the skimmer can be used in
place of the biological filter(?). Or is it that the 204 type
cannister filters are bad news but other biological filters are OK(?).
One dealer we consulted suggested under-gravel filtering, but others
seem to agree with the first and recommend cannisters?

Since our original posting, we visited a dealer we haven't been to
before and he too recommended a skimmer, but in addition to the
existing filter setup.

Help!!