Any reason why you dont want a sump? I thought the same way when I first started and now couldnt live without it. lol
Specially with a 125g, you will get better filtration and have an overall better and more stable system if you run a sump.
180g Reef - 60g Rimless Reef -90G FOWLR- 125g Malawi Cichlids- 40b REEF- 34g Fresh Planted-working on- 20L FOWLR- working on
I have a mix of many different saltwater fish amongst my tanks, but I love my Tangs most of all.