I am running a 55 gallon sump under my 220 and it's completely silent with a herbie style overflow (mine is actually a dual herbie). The only thing I can hear is the hum of the RIO pump I that I'm going to replace with a DCP 8000 (I already have one of these DCP 8000's, as my setup is a dual pump setup, and it's also completely silent). Once the RIO pump is replaced I don't think I will hear anything unless I really try to. I am pushing about 1600gph through my tank.
Definitely look into the Jebao DCP pumps as they are extremely quiet (they are two generations newer than the DCT pumps) and are very adjustable. I can use the settings on my DCP pump (can be adjusted between 30 and 100% by single increments) to tune my herbie overflow.
How big is the tank?
Or you could go with a 75 gallon sump. Bigger is
always better.
I was able to set up a completely DIY sump for about $400-450, and it's the best filter I've ever owned. After a month of waiting for deals on Craigslist, I found a 75g sump that needed resealing for $25. After adjusting the baffles to my need, and creating a drip plate, with $100 worth of acrylic, I was able to put it media, which set me back another $50. Plumbing was about $100, and I picked up the pump from Lowes for around $125.
Sumps are easy to set up, even if you start with a bare tank. The baffles aren't very complicated, just make sure the water flows in the opposite direction of the previous baffle (over, under). Plumbing also isn't that bad. I have two 1" bulkheads on my 210, which is considered below average for a tank my size, although they keep up with my 1400gph pump fine. I'm no expert, but two 1-1.25" drains should work well with a tank that size, depending on the flow you want.
Maintenance is also quite simple. Replace the socks every couple to three weeks, and clean the bottom of the sump every few months.
If you don't want to go this route, a single eheim 2262 would cost less money (than two FX6s), and would filter the tank better than the FX6s.
