I currently run a fowlr. Its a 100gallon tank with 65kg of live rock. The live rock parforms most of my filtration. I also run a protien skimmer and reccomend you do the same as they take out so much rubbish.
A fish only tank is easier to maintain than a reef as you dont need to use RO water and you need not do so many regular water changes to keep nitrates down as you need to in a reef.
Look into setting up a sump. The sump (which goes under you tank) can house your heaters, skimmer, uv more and more live rock (which the reccommended amount is at least 0.5kg per gallon.)
If you have it as a fish only, you can also look into wet-dry / trickle filters. Though not popular with reefers due to the fact they create nitrates, they are a very good method of filtration for F.O tanks and are cheaper than buying all that live rock.
When I upgrade my FO to a 200gallon I will be running it with approx 100kg live rock, a wet dry filter, large protien skimmer and uv.
Hope this has helped, or maybe it has just confused you more
josh