Controlling pump speed with Nexus Rheobus
 

I've got he MCP-650 and I'm getting annoyed with it's semi-high-pitched hum. I'd like to control it's speed with my Nexus Fan Controller but I read at Danger Den that the pump needs at least 18W per channel from the rheobus, whereas the review of my fan controller says it's channels will support from 15W to 18W. Is this cutting it close?

I'm not sure how rheobuses work, and excuse my ignorance, but is 18W the wattage at full speed? Meaning if I turn the dial down it'll go below 18W and mess with the pump from then on?

Do I need to get a new rheobus?

Quite frankly, I wouldn't trust the Nexus. I have a black one for my 5.25" bay and the only fan i'm controlling with it is my 92mm Tornado cpu fan. The darn thing has a mind of its own. My fan doesn't even go up to 4800rpms anymore (more like 4600rpms now with the knob turned all the way to the right) and sometimes i'll catch my fan speeds all the way down to 1800rpms! Not to mention it has an annoying electrical hum....but my fans usually overpower that noise.

I can't wait till I get my new watercooling setup so I can just use the Nexus for a couple case fans and that's it.

Hmm... I don't have any of the problems that you have with the nexus. I tried attaching my pump to the nexus and it worked... sorta. When I decrease the pump speed the sound actually INCREASES in the sense that it gets higher pitched.

Yeah....

My super flower fan master was supposedly rated to the specs DD suggested. The channel that the D4 was on cooked in seconds at anything less than 12v, and got pretty hot even at 12v. That channel quickly failed, and stayed that way.
I switched back to my silent eheim and didn't notice any temp gain.