Neptune Cor-15 RPMs are always fluctuating...is this normal?

[Z Burn's Reefing]

Hey All,

I just upgraded to a Neptune Cor-15 as a return pump. I noticed the RPMs (running at 60%) are bouncing all over the place. I accepted small jumps here and there, but over the last 24 hours the RPM high has been 2210 and the low has been 2110...nearly a 100 rpm difference. Is this type of fluctuation normal? The pump is pretty darn clean, only a week old...do these pumps have greater stability if i turn it down some? Or perhaps turn it up? I was hoping for a return pump that was really tuneable and stable...kinda of disappointed...

Thanks for any thoughts and experiences for those who have run the Cor pumps.

 

[gbru316]

I find mine does this too. I occasionally have to retune my overflow because of it.

 

[Z Burn's Reefing]

I find mine does this too. I occasionally have to retune my overflow because of it.

Thanks! Yea....I am running a red sea tank and the constant adjusting of the down flow value (which controls water level in the overflow) is tiresome. I was seeing the water level dip a little in the overflow and so I adjusted the downflow value, but perhaps if I let it ride, the pump will increase RPMs again and balance itself out. Today I dialed the pump down to 40% to see if stability is a little better at lower gph.