I don't run any checmical filtration on my 55g anymore. I have an eheim classic 2217? that runs all biological, and an eheim 2213? that runs ALL filter floss. weeky water change of 10 gallons. My water has never been clearer since the floss!
Careful with HOB. Any surface turbulance will cause CO2 loss. a little bit of surface movement isn't bad, but you don't want churning.
I've heard UV is bad for iron, but I use it, and my iron levels are fine (of course I do supplement it) It's something you'll have to play with on your own-I don't know enough about it.