In the event of a power failure, the wet/dry won't make any difference at all. In fact, if the media dries out, it could contribute to the problem when the power comes back on. A
HOB filter is really not needed on a
SW tank that has an adequate amount of
LR. You could run it with no media for extra circulation and perhaps use it for
AC once in a while. The bio wheels on the Penguin and the bio-media in the wet/dry will contribute to nitrate levels which you don't want. What I would suggest for your tank is more
LR. With 60lbs, you are at the lower end of the curve for an adequate amount of
LR...1 1/2-2lbs per gallon is recommended. The
LR will continue to filter even if the power is out. Another good investment might be a power inverter so you could run a couple of powerheads while the power is out. If not that, a battery air pump and an air stone would at least help keep
O2 levels up in the water.
JMHO.
You might want to research
DSB's also. You'll find, by using the search feature, a lot of info about that on this site and links to other sources of info. Increasing your sand bed depth to about 4" can help control nitrates and allow for better biodiversity in the tank. Some swear by the
DSB and some swear at them...something for you to consider anyway.