orange,
The BM is internal and the build quality it not that bad, not as good as an ER that is true, but not bad. The BM250 will still pull more skimmate than an ER RC180. The reeflow was in the original post. The Orca has three H3 pumps, each pulling around 800 lph, so 2400 lph on a 12 inch body that is 32 inches tall compared to 960lph on an 8 inch body that is 24 inches tall, there is really no comparison and they cost about the same. You could probably ditch the H3 pumps and use 2 eheims for around the same cost (but less air draw).
I apologize if I was a not being civil in a post, but when someone says I am lying it bothers me.
I will say this again, ERs are good skimmers, but for the cost there are much better alternatives out there.