Wet drys are very good for a reef. They allow the Microbes to develop that provide nutrition to the tank, and eat the Lousy Ammonia. As far as the Canister or sump. You can go either way.
The reasons that I like a sump compared to a canister filter
1. Allows you to expand your tank more (Like being able to put the skimmer on the sump and not the back of the tank)
2. Clean Install. (this looks a lot better then having diffrent filters canisters and skimmers all over the place.
3. Ez water changes.
4. If you need to, this is where you would mix in your Chemicals for the main display tank
5. Allows Bigger and better equipment to be put on the current tank. This way if you want to upgrade you are well on your way
6. More filtration options in a Sump. If you want you can put a "Drip plate" above the rocks and a filter pad on the drip plate. Now you are pre screening what has already been screened by the Sock.
7. Socks for the Sump are less expensive then filter pads.
8. Refuge. You can add a fuge to a sump to provide natrual Kelp and other "Good Algies" to the tank and good Critters "Pods"
Your best bet is to build your own Sump.
For your 55g you can use a 30g long for your sump.
A 30g long is about $50
Do a search on Youtube for(( Reef Tank DIY Sump part 1 )) andd part 2 of course.
((((((NOTE You DO NOT HAVE TO DRILL IF YOU DO NOT WANT TO
))
I followed the instructions from this and it works BEAUTIFULLY.
Really you are only looking around $80 if you build the sump as apposed to $200.
But that is your best bet
